The only thing we know about the Daedric princes 'power levels' compared to each other is that Perylite is the 'weakest' and Jygalag was getting so powerful the others came together anbd cursed him into Sheogorath.
I was born of your dreams. If you believe in me... ...there is nothing I cannot do
I wouldn't even call the return of the Dwemer unlikely. The "last living Dwemer," could easily be construed to mean the last living Dwemer in that plane, under those circumstances. The Dwemer could also return as not totally living. There's a lot to be done with it. That being said, I'd only ever want it done if it's done right. I think they re-introduced dragons without making them lame, and they'd have to do it that way.
SPOILERS SPOILERS SPOILERS
That being said, I'd much rather use the hope of the Falmer not being totally wiped out (as hinted by the guy in Skyrim) to get them back and playable than have the Dwemer.
Yagrum (the last living dwemer) spent thousands of years searching. Was capable of inter dimensional travel... and could not find a trace of his kind.
Whybwould you call the return of the dwemer unlikely when for the entire series, there has only been one living dwemer, and confirmation of dwemer being extinct?
Thats like expecting the dinosaurs to be likely to return, because hey, maybe theres dinosaurs on jupiter! :p
The road goes ever on and on.... Time to replay ff9 and Grandia... whee