The FT is reckoning on a split across the Eurozone:
"But, as a small city with a population of less than 700,000 people, Frankfurt is seen as provincial and unpopular with staff. Dublin is English-speaking and attractive on tax grounds, but it is a relative backwater. The most likely outcome is that foreign banks with large operations in London will shift staff to a spread of eurozone locations where they already have operations — including Frankfurt, Dublin, Paris, Warsaw and Lisbon. That would fragment the financial services industry in Europe, potentially weakening the continent’s ability to compete internationally."
I can't say I'm afraid, I was told so in confidence by someone in HR at a major one. They'd already delayed salary reviews etc. over the last few weeks for this reason too.