Zero chance Paris pulls a large percentage of these bankers. They do have a lot of bad labor laws and quite high taxes, both of which have contributed to France having a very stagnant economy (both in terms of innovation and growth) for decades. In real terms their economy hasn't expanded in nearly 25 years. The centers of power in Europe are still by far in Germany and the UK. French voters have noticed the problem, which is why their Socialist leader recently had a 4% approval rating and the far-right is making big gains. The same disastrous policies that have left them with a broken economy, will keep the London bankers away. There are half a dozen other major cities that will get a look before Paris.
Not to mention, France is increasingly an outlier in Europe with a punishing corporate income tax rate (33%). Most of their European competitors have been slashing that rate the past decade plus: Netherlands 25%, Spain 25%, Austria 25%, Sweden 22%, Denmark 22%, Portugal 21%, Finland 20%, UK 20%, Iceland 20%, Czech 19%, Poland 19%, Switzerland 17.9%, Ireland 12.5%. The average across Europe is about 20%. Why would an international bank want to be there, except for local French business purposes?
Not to mention, France is increasingly an outlier in Europe with a punishing corporate income tax rate (33%). Most of their European competitors have been slashing that rate the past decade plus: Netherlands 25%, Spain 25%, Austria 25%, Sweden 22%, Denmark 22%, Portugal 21%, Finland 20%, UK 20%, Iceland 20%, Czech 19%, Poland 19%, Switzerland 17.9%, Ireland 12.5%. The average across Europe is about 20%. Why would an international bank want to be there, except for local French business purposes?