If I want more dragons I can go to Dungeons and Dragons..if I want Elves, I go play some Warcraft or some other stuff.
Or on a side note, perhaps I can join with vampires and kick some pathetic human ass and kill some stupid elves. Now wouldn't that be a sight.
And if you want vampires, go play Vampire Masquerade.
Skyrim is not based around vampires, as World of Warcraft isn't based around elves (most fantasy games have elves anyway, WoW is not unique in this aspect)
But, Skyrim
is based around dragons, but as that threat is dealt with (as far as we know), then anything is possible. If Bethesda wants to bring back the snow elves, they sure as hell can.