A high land value tax moves the problem around (instead of young people not being able to buy a house, older folk can't afford to keep the large one they spent their lives in).
In the process, it makes land completely unappealing to rent-seekers while incentivizing high-density development of desirable locations.
> older folk can't afford to keep the large one they spent their lives in
This is only a problem if you believe older folks should continue to live in big luxury houses for a pittance (read: gain the benefits of luxury without having the detriments of luxury), or the country does not have enough smaller housing for them to move.
In situations where housing is severely constrained at the cost of younger people, leaving old people in their large houses should be the last of your concerns. Doubly so for any social structures where older generations are extremely reliant on younger generations (almost every democratic, socialist or communist country).
In the process, it makes land completely unappealing to rent-seekers while incentivizing high-density development of desirable locations.