I am here because i googled this same question, but i think i
have a hypothesis of my own, which would be that yes it should stop
eventually. There are vast areas of the Earth that have no area of
isostatic activity - check out the wikipedia on post glacial
rebound and there is a map that shows regions. I would imagine that
this since this is an energy state issue , balancing with gravity,
that the system would tend to settle as soon as possible. If we
look at varying geologic areas effected by isostatic rebound it
seems like they occur, in then remain static. iso static , a series
of teeter-totter weights and balances, on the surface of the
crust.