Or they could sell to a condo developer, get a brand new unit, with lesser maintenance needed, in the same location. It doesn't have to be a binary choice between "sell and move away" and "stay and keep prop 13".

With Prop 13 and zoning restrictions, "sell to an upzoner" is essentially off the table.

Also an old couple who have been renting since the 70s could be evicted until state-wide rent control was passed this year. No one cared about them this whole time.

It's also not clear what things like commercial properties or family farms have to do with "keeping old people in their homes". All these are covered under Prop 13.