If any races were to try and take over Skyrim, I think it would be the Redguard and/or Breton in my opinion.
And they would have hell to pay from the Orcs, Nords, and now-occupying Dunmer.
Orcs because this Redguard Breton alliance attempted to sack Orsinium already, and they seem to get along with the Nords pretty well. (see: Lord of Souls)
Nords because well, it is their homeland. And the Dunmer because the Nords have shown them great kindness by basically giving them Solstheim and allowing them to partially occupy Skyrim. These once ancient enemies now have somewhat of an alliance going themselves. Which I absolutely
love. Considering my favorite three races go: Dunmer, Orsimer, Nord.