Humans are sentimental creatures though and "grandma has to sell her home" is a powerful image.

I think a good compromise, that would also allow Prop 13 to be phased out for good, is to allow primary residences below a certain value to deduct taxes against the home value up to the limit (ie defer payment until the person dies, then the estate settles the debt, most likely out of selling the home) and at that point not owe more. That way grandma never has to leave her home prematurely, society still captures the lost value of underutilized land somewhat, and there is no ridiculousness with commercial properties, inheritances, very wealthy people paying no taxes, etc.