Could go kind of dystopian...
Breton/Nord/Imperials united in a series of wars against the Mer, and so became one mottled multicultural race.
Altmer and Dunmer still exist distinctly, since they're so different.
Bosmer side with the beast races, including the Taesci and such, who are all essentially deep-ecologists with strict regulations on terraforming.
Dwemer re-emerge by this point in time as an advanced race, and largely the superior enemy of the other races, can manipulate other races to assimilate as varied forms of centurions and other such cyborg agents. Though mostly only the Dunmer are willing to go with this transformation. The Dwemer can also destroy entire planets, but only demonstrated this power once and it's rumored if it was even caused by them, how they accomplished it, or if they could gather the resources to do so again.
The worshippers of the divines are considered cultists, except by Altmer, and daedric lords walk freely on certain planets contained by Altmer technology. The Dwemer failed in their earlier attempts to contain the daedra (in fact they released them in the first place and invaded their planes) and this gives the High Elves a bit of an edge, creating an incredibly uneasy stalemate between all races.
