I'd assume that many of these copies are disappearing into collections for the foreseeable future, which should keep prices high. Not sure they can continue this wild upswing, but they'll likely stay strong compared to recent years, but who the heck really knows?
It might feel bad to have not sold your copy, if you have one, when prices are really strong and then buy a new copy after they cool down. It might also feel bad to sell while they are strong, thinking no way they'll get stronger, then regret that very much in a few years once the X-Men are deep in the MCU. *shrug*