i recently searched for a new shared apartment and there were plenty of offers that were looking explicitly for professionals and not students because of the reasons you stated above. I also know of older ones living in a shared apartment (though not as a rule). I can imagine moving together with a partner or switching apartment because of the reasons you mention above, but living alone is not something i want to do. But i understand there are reasons some don't want live in a shared apartment.

I think what i want to say is that for most living in a shared apartment is not a thing out of necessity anymore, but out of choice