I think life is hard enough for older women without being forced to downsize if they don't want to. A friend of mine obtained a council house when her husband disappeared, and brought up her four children there. She has been left with a daughter who is clinically depressed and has caused no end of trouble over the years, and her neighbours have been wonderful. However, the daughter is 30 and also has a rarely-used flat elsewhere, so not a registered tenant, and my friend was worried sick that she would lose her house and have to sleep in a living-room during those months when her daughter is particularly bad. As said previously, she has been told that the new rules will only affect newer tenants. She will apply for a flat when she can no longer cope with her garden.
I think men are quicker to downsize when they are on their own, they aren't thinking of family members needing to stay overnight in the same way that women are. We have an elderly uncle who lives in an incredibly expensive area and downsized last year to a small flat, he is always saying that we should come and stay in a hotel nearby and I don't think he fully realises how expensive it would be for us to do so.