The abandoning of the major cities looks like a permanent event. London is by most accounts a zombie city, the centre is dead, footfall is 10 % of what it was.
Canary Warf an extension of the City, has a daily population of 120,000, as of now @ 7000 are coming in. Docklands and Heathrow the two main airports are running at under 10 % of capacity, same for hotels, mass layoffs are just round the corner.
Unless something happens soon and with our current cretins running the show, that is next to impossible, London will collapse financially.