I think I read somewhere that, as with every other tourist attraction, BP lost a lot of revenue due to Covid. So I think it's already bringing in quite sum from allowing tourists in.
I don't think there will be the same pressure to live at BP as there was for the Queen. Clarence House must be much easier to maintain as a private residence, and Buckingham Palace could easily be used as a place for events more than anything else.
Charles can always stay there for state visits etc (do people like the President of the USA stay there when they come for state visits?) as necessary, but I don't think there is a need for him to live there.
There must be so much history in the building that it may be better served by being open to the public most of the time, save for when it needs to be closed for security for state visits etc.
I do wonder what will happen to all the Queen's homes though. She has Balmoral, Sandringham, Windsor and BP.
Charles has Highgrove and Clarence House.
They need to keep Balmoral as a presence in Scotland - plus they all seem to love the place. Will Charles keep Highgrove? It seems convenient if Camilla does spend a lot of time at her home nearby (I think to see her grandchildren), but then there's still Windsor and Sandringham.
Maybe W&C will take Sandringham as an upgrade from Anmer Hall? Plus it looks as though there is a suggestion that they spend more time in Scotland to try to solidify the union.
Someone on a previous thread suggested that H&M would be offered Highgrove when Charles became king, but that seems unnecessary now, as they look unlikely to spend much, if any, time in the UK.
Do they rent out any of these places? Like Anmer Hall, wikipedia suggests that it was rented out prior to the Queen gifting it to W&C.
You can't really rent out Windsor castle though!