I am very fond of the High Elves, they are pretty awesome.
The Thalmor I am also fond of because they are great bad guys - and I love great bad guys (unless I play a character who for some reason sides with them in which case the character would think they were misunderstood good guys, straight good guys who don't care what lessers think or is mercenary and wants to be in with what looks to be the winning side). They are doing everything right as bad guys to make me hope the next game is in some form as follows:
Some significant time after the events of Skyrim your character opens his/her eyes in a Thalmor prison ship/prison wagon/line of condemned men on their way to the gallows, somehow escapes his/her fate and goes on to discover their destiny to save the world from something that might bring them into conflict with the Thalmor, possibly redeeming them or defeating them in the process or possibly, I guess, making their vicious speciest Empire more efficient and strong.
I don't think it would have a plot that out and out has the character fighting the Thalmor if they were a dominant power. Morrowind, Oblivion, Skyrim was more about an individual facing something that threatened the existing power structure and everything and in the process you interacted with it and shaped things in some way (Great Houses, Empire, Empire and Stormcloaks - maybe doing things that would seem to strengthen or weaken or change them)