I'd imagine at a certain point it's going to become an issue of what would it cost to get it operational again versus chalk it as a loss and be glad with the decades of cash flow you got out of it and call it a day.
The Myst idea was cool when Myst was hot, but that franchise has kind of died out completely. Had they gone with it, I wonder if the attraction would be stale by now because the buzz is gone. Pop culture flavor of the week doesn't really work for an upcharge concept at all, unless it's just temporary.