It remains to be seen whether supporting regulations are a good enough proxy to avoid ring-fencing. The EU has now officially scrapped the proposals of the BSR bill.
I guess they have a valid point in the fact that a number of "parallel" regulations from BCBS 239 to MIFID II to Volcker to FTRB is slowly but surely putting the checks and balances required to protect the average retail customer.
However, it's only a matter of a few years to see what works (and what doesn't) as the 'Big Four' in the UK go ahead with their ring-fencing. And I'm sure once they figured out Brexit (or not), the regulators on each side will have ample time to exchange notes on the effectiveness of their respective regimes.
U.K. pushed forward with a similar policy that will take effect in 2019 and was championed by John Vickers, who headed the Independent Commission on Banking. The proposal will lead major U.K. lenders including Lloyds Banking Group Plc, HSBC Holdings Plc and Barclays Plc to ring-fence their core banking services used by retail and small business from their investment banking divisions.