One answer might be a government-mandated expanded rental scheme, requiring investment funds to hold a percentage of assets in apartment blocks. I don't know how it works in many European countries but they seem to have or did have larger rental sectors than ours which worked satisfactorily.
The current system of rental ownership is not supplying the market needs, from what I see in the media. Indirectly it is taxpayer funded, but it seems to me the taxpayer funding might be better employed in closely controlled corporate or mutual funds.