The obvious thing to replace it with would be a towel warmer, but that would require running an electric line if the heater is gas and not electric. However, if you have basement or attic access, that won't be that difficult to do. They do take quite a bit of amperage though, so if the home is old enough that it has a pink bathroom, that solution might not be a solution until you upgrade the home's electrical.

If these are combustion type heaters be sure to have them checked before use.

Cracked heat exchangers on gas fired through wall heaters are painfully common as the things age.