DailyFail London is already a global player towards Asia / America, and the EU passport was part of the competitive advantage in some sectors.
Obviously not the UK high street operations of HSBC who are no more an Asian bank than Swires / Cathay or Jardines are Asian companies. Western companies focused on Asian markets, yes, and exploiting asian connections / power networks and cultural insight , but western nonetheless.
China has already been very vocal that it will direct it's financial sector business into Europe, if the UK loses the passport, unlikely the City will retain the Yuan operations for instance. It is already closer to Merkel in spite of the Osborne brownnosing.
Some sectors will gain, private banking, wealth management for instance are looking forward to deregulation and being able to wheeler deal more on behalf of the world's criminals and oligarchs. I am sure there are a fair few traders and hedge fund managers toking forward to returning to the buccaneering ways of the 80s.
However the real meat of the city of London, not just American banks but the likes of UBS (who are also one of the bigger players in Asia) are known to be almost certain to go. They will take their big dick swinging front office bankers off to Paris or wherever but in my London suburb, most people are not that. They are in middle management back office roles, in service industries that provide them with business to business services, and then on the back of that there are all the SMEs (small businesses ) that survive on the back of their salaries.
Over Christmas it has struck me that we are already back in the 80-s and 90s in terms of the numbers of homeless on our streets, Cardboard city is building back up at Waterloo.. It is such bollocks to other London as somewhere that is not a cross section of British society and one where life is going to be much bleaker post Brexit and post having a workforce that are diverse and skilled.... And that will translate into less tax income to support the rest of the country... I don't argue that the UK wasn't unbalanced but shooting all our assets was not the answer