Earlier quoted context omitted.
If there is market incentive to move banking to Holland, it will happen. The bankers will move where the jobs go, they don't have much say in the matter.
The large salaries paid to bankers are based on the idea that elite bankers are a rare and precious commodity - one that it is worth paying for. Presumably this is elite bankers are the most connected and collaborate to rig markets best. Presumably if a bank moved to amsterdam, it would not be able to hire the top bankers and would be left out of important money making schemes like the recent Libor conspiracy.
Big enough market disruption can easily tip the scales. And leaving the EU trade zone is pretty destructive for banking and European HQ beachheads in London.