However I don’t necessarily see your point, why people giving up on being landlords is necessarily going to result in those properties being sold to other landlords, if they could still make money being landlords then surely they would keep at it.

Think of most commercial properties: usually, when a business closes, another of the same type will occupy that spot. Generally the newcomer feels they can cut the margins enough to make a profit. (Often why you’ll see something family owned being replaced by a corpo chain version.)

As I noted, some houses will enter the private market but I’d expect the much more likely buyer to be a developer or corpo landlord.