Thinking of the carrot versus stick, I would prefer lone tenants in properties that are now very large for them to be offered incentives to move/swap to smaller properties, rather than be chucked out.
Those that take the offer wouldn’t feel resentment at being moved out against their will and there wouldn't be the precariousness of time limited tenancies, which lessens investment in properties and neighbourhoods, thereby reducing social cohesion.
A certain amount of family sized housing would be released through this, which would justify the cost by the improvement in living standards for families, thereby lessening the need for other social service input.
Those that are so emotionally invested in their family homes could stay - but for these, the offer of voluntary, well-financed and well supervised and contracted lodgings schemes, to house some of the singles, single parents, elderly etc, that opt in.
It might be successful socially too, creating alternative family groups.
BTW, how did that multigenerational council house in Margate work out? It sounded like a good alternative scheme, to house three generations of the same family, who would otherwise have had three separate council properties, in one large house. (I think they all had their own spaces as well as some communal space) Again, a voluntary similar scheme might be run… built in babysitters and support for aged rellies.
Building more social housing (on brown sites) should run along side this, as should conversion of a proportion of empty High Street and office properties into living and public spaces.
And no more RTB.