Not all OO or investors will want or need to maximise the utility of the asset (wear and tear, increased maintenance issues, public liability issues, legislative/regulatory problems etc etc).
I think one of the biggest would be the tax implications / loss of CGT exemption.
Things would have to get pretty damn extreme before families let 'strangers' live in their houses with their children. It's like telling someone to go without a mobile phone.
I agree it will occur to an extent. Maybe 10% of capacity? Again, another impossible to measure emotional factor. At what dollar point will people give up their privacy/security/lifestyle want? Time will tell.