Maybe they're brought back as the tools of Alduin to destory the other Mer and Humans!!!
...i thought that was the
dragons' job?
seriously, people... you cant just throw in ideas that dont make any sense.
as interesting as the dwemer are, they're one of the BIGGEST mysteries in TES... if they take that mystery away, we'll have alot less to talk about.
if they ever do come back, i'd rather wait until bethesda has the time to dedicate a whole sequel to their return, not just throw it in as an expansion for skyrim or whatever.
what do you want... a few-hour long quest that makes the dwemer's return nothing all that grand, or wait until someday when an entire game can be devoted to it?
also, they'd need another huge mystery to replace the mystery of the dwemer with, otherwise we'd be losing more than we gain, i think.