Bankers have no special skill set, they are not "key revenue generators". There are, literally, hundreds of people who could replace every last one of them. If every banker left the country today (which is, of course, absurdly unlikely) they could be replaced by people on a fifth of the salary/bonus who are every bit as good at the job within a month.
Bankers don't profit because they're uniquely skilled, hard working individuals but because the nature of the game means they win. It's like paying croupiers vastly inflated bonuses because their table keeps making money for the casino.
Frankly, we should be looking at ways to make banking systematically less profitable so that they money accumulating to banks is more in line with their actual value to the economy and society and the problem of bankers bonuses would look after itself.