I know a lot of old single folk living in houses with 3 or more bedrooms and I think they would not want to move to down size because even if they only have a friendly neighbour or two they would miss them. Also, they would miss the association they had with their loved ones in the house they're in. A major factor. The main reason they would move is to be near their offspring certainly not just because they want to ownsize. One of the main contributors to an old folk staying put is the stair lift. In the past a flat or bungalow was needed but not now with a stair lift.
I helped a friend downsize by renovating her home and then her bungalow and for somebody who is 'delicate' it would have been a traumatic experience. But she did it because she had a lot of help. For an old dear not having a good friend/relative near by to help out she would find it difficult. My neighbour had it easy because she moved to a granny flat and sold her home. So, for some, its easy but for most it would be to hard---and surprisingly they know it. Many of them are wise enough to know that staying put is okay for them.
I am heading that way myself with good health etc., but anything can happen to spoil things.
I think that when people talk about what old folk want they should do it from the old folks position of wealth and health because its a lot different when either are not there.