The Bank of England has made the decision for the UK not to be a part of T2S so no worries for UK FS firms. I presume this research was on a main land Europe view and then only those countries that have agreed to enter. I wonder what the cost would be if the UK was in? Huge i expect 

Agree with the sentiment about short- mid term cost to the industry. Any broker-dealer operating in pan european markets have to reconsider their settlement and clearing model. Intra-day liquidity will be an issue as if you use an agent bank model largely speaking you are shielded from the capital/ Collateral requirements currently. This will change in the next few years, so the cost of doing business will rise. There is also an opportunity to rationalise your agent bank network and look at the overall cost base for clearing and custody. Asset servicing provision also a factor to consider as well. Messaging will need upgrading from ISO15022 to ISO2022 if you want to be direct participant and therefore realise more of the benefits offered by T2S. I don't think any firm should assume the do nothing approach will be suitable. Would welcome other views on the subject.

Also, it would be oversimplifying to say that T2S messaging just "is ISO 20022". While some of the T2S messages are implementations or variants of messages that are already fully registered under ISO 20022, a good number are new messages that are not yet registered - and there is a third group which will never be registered, being wholly specific to the T2S project, though they will use ISO 20022 syntax. However this is all currently being documented in a SWIFT MyStandards project, we understand.

Savvy T2S participants will be able to mitigate their costs by judicious selection of their VANSP.