I read it all.Ah yes.. "according to the the cycle of life in the western world".. I couldn't have said it better myself!
I see things differently. I don't see how downsizing from a three bedroom house (the average) to a smaller two-bedroom unit (often in a more urban area) is helping much. In fact I would say grandparents and parents not having that stability and space to help out other family members whether that be baby-sitting so other family members can work, or a space where family members can stay in times of crisis (illness, a relationship breakdown etc) is doing way more for society than if they sold up.. and the idea that you need to wait until they die to free up a house is silly as they are still going to be taking up a floorplan and living somewhere.
I work in the housing and homelessness sector, and I see a primary issue causing homelessness being not having a family home to go back to when the shit hits the fan. I know this is not as simple as your parents having a spare room, but it sure helps. I think something lacking in the "cycle of life in the western world" is the break down of family relationships and the subsequent support and stability that they provide. Again, grandparents/parent having a spare room doesn't guarantee this, but it doesn't hinder it either.
I would argue that the actual affect of our grandparents staying in their home longer is a very very small part of the problem.. but it is a convenient one for policy makers and the like as it takes the focus off the bigger issues in the "cycle of life in the western world".
Just my opinion though, and I respect yours. I didn't mean for my short response earlier to seem like I was being dismissive - more that I had to get to work!