The plight of a person in such a situation should never be discounted, but it's simply not a viable option to guarantee any land holding to be held in perpetuit

The plight of a person in such a situation should never be discounted, but it's simply not a viable option to guarantee any land holding to be held in perpetuity regardless of ability to pay for its rent. If you ration off land this way (quite inefficiently, that is), you cease to have enough land for everyone else. Which causes a class of suffering far greater than granny deciding to sell out, and move to a condo.