When Core Banking solution (CBS) was designed in the late1990’s, it was engineered to connect to the different branches of the bank using a central database and ensure proper accounting to generate the General Ledger. It removed the huge ledgers in the Bank where manual posting was done by  staff and eliminated the branch-based accounting software (Total branch automation software) which assisted the front office/tellers to perform routine/repetitive transactions.  The initial vendors of the software worked /co-build the software with large banks who provided the requirements to convert the manual ledger operations into an accounting software. While the intention was to perform online real time accounting, some of the processes which led to this accounting was also embedded as part of the CBS package. The focus of the design centered around the different business lines prevalent in Banks at that point of time- CASA and liabilities, Assets and Trade/foreign exchange- primarily from an accounting perspective.

From a concept perspective, it succeeded in eliminating the manual accounting, improved transparency in reporting from a Bank/regulatory perspective and assisted the customer in banking anywhere anytime,  since all accounts are linked to a centralized database. Banks whose staff devoted larger time in reconciliation, manual interest posting, and manual General ledger creation heaved a sigh of relief where errors were minimized, data available in a software rather than ledgers, reporting was smoother. From a customer perspective, passbooks and statements were provided in an automated way, balance information and withdrawal was possible through an ATM anywhere located in the same city where the account was opened/outside,  with an interface to Core Banking solution (CBS),  thereby increasing trust in the banking ecosystem.
From a Banking perspective, many of the operations could be moved from branch banking to centralized cell enabling front office staff to focus on customer service and cross sell/ business improvements.  The concept of front office/back office originated where a separate set of teams focused on back-end activities-, product creation and innovation, clearing, loan operations, trade operations, account opening, audit, reconciliation, reporting and MIS etc. With more information and data at the back office, it paved the way for new product innovations resulting in launching of more products, thereby increasing business/profits for the Banks. The CBS helped the Bank to globalize/localize products which are fit for purpose for the customer bringing customer delight. 
A decade later it was realized by the Banks that the CBS is not able to cater to the business areas where more processes/rules are required for eg, payments and trade operations. While CBS was able to perform the accounting, it was not able to build the rules/processes required for the business operations- for example payment rules based on customer, amount, time, network, charges etc. While the conventional Banks who adopted the CBS continue to operate /work with the software for accounting keeping the rules/processes for payments/trade outside, few of the Banks purchased specialized software for these businesses which could typically cater to these processes and interface with CBS for accounting. The specialized software was designed to perform the processes/steps/rules/exceptions and lifecycle activities for the specific business which could finally culminate in an accounting. While initially payments moved outside the core, trade and lending operations followed the same path for these banks leaving aside CASA, liabilities, and accounting within CBS.
From the beginning of the last decade a set of new businesses emerged which included private Banking, cash management, microloans, distribution products and gained popularity with Banks because of the visibility for new avenues of business. This was either forced through regulations or because of market factors and Banks began to depend on new software solutions reducing the dependency further on core banking. The era also saw the emergence of digital and self- service channels where Millennials/new age customers depended on web browser/smart phone to perform banking transactions. The older generation of customers though a little reluctant, moved towards these digital channels for limited transactions over a period.  A smooth and easy interface with CBS was required which resulted in CBS vendors forced to build those APIs/smart interfaces. This also ensured that the multiple security and compliance protocols must be built in the application to reduce frauds for transactions originating external to CBS. Customer experiences , customer behaviour and customer needs for banking changed drastically during this decade.  
With the emergence of Covid 19, the footfall of customer visit in the branches of the bank further reduced globally and more and more transactions were performed digitally creating a heavy load on the CBS software.  The digital transactions increased manifold during the Covid era thanks to regulations, digital options available for customers, e-commerce and online payment options, and the forced need for the consumer to transact with Covid restrictions.
To conclude, the redesign and modernization of Core banking is a priority in the current decade with evolving changes and considering many factors of banking transactions which moved from branches to mobile to social media to alternate channels. It has to move away from accounting-based CBS to rule/process based with accounting embedded. While the initial design was primarily focused on accounting, the rules/processes/exceptions for the product/account lifecycle at various stages must be factored to meet the needs in the modern era.  User experience was not a factor as part of the initial design which resulted in reduced usage of the software and with process/rules/steps, the user experience must be rewritten.  From a menu option driven approach, process -based approach to inform the user on the tasks performed/to be performed/next steps etc. must be available in the dashboard based on access rights, rules and privileges of the user. With increasing digital needs, relevant API s which are based on industry protocols need to be available for fulfilling relevant business life-cycle activities so that transactions can be performed digitally any time anywhere. Decoupling of multiple business lines- liabilities, trade, payments, lending, cash management and independent self -servicing functions for multiple areas within the current core for pricing/accounting /masters need to be considered while redesigning the software. Dependency on limited databases and platform as per the initial build need to be enhanced  and modernizing the core by enabling to work with any platforms or databases has to be enabled. Modernizing the code bases to make it updated/contemporary with new programming languages so that there are no limitations for future changes for conversion with code convertors/tools has to be adhered. With increasing work load in the core ,and likely to be tested further ,because of digital momentum, CBS must be enabled for meeting increased volumes and scale. The CBS must comply with global security compliance and standards. The version upgrades, installations and changes must be smooth, just like an automatic patch update in a mobile phone except where major changes and an upliftment is required once in a decade or so.  While the initial CBS was able to deliver functionalities/code without analyzing the end usage, the new CBS must take a reimaged approach with end user in mind. From an online transaction processing platform, it should understand the realms of online analytics to provide meaningful insights at the transaction originating point/processing cycle.
There are multiple CBS software’s which are tested, proven by way of functionality, successful in selected markets and many new CBS which has cropped in the recent past purely based on new technology, rules, APIs and yet to prove their credentials. The CBS has to keep updated with the market requirements and newer innovations and technology uplifts in the banking/financial services sector and a new age Core which is flexible and agile has to be designed which can open up to accommodate the eco system players and services and provide holistic solution to Banks. With changing banking landscape , the CBS must be redesigned considering multiple factors and such a software can be successful in the next decade or else banks would explore alternate ledger systems, process /rule systems, API systems and build the technology /application suited for their banking needs from the scratch combining the above systems with/without a CBS software.