Arguably the single biggest reason for Witcher 2's success is that it has virtually no competition. Every other "RPG" series out there has been moving more and more toward AA/FPS, and RPG fans have grown more and more desperate for another great game. And the funny thing is that Witcher 2 still isn't that game - it's just the closest thing to it that we've seen in a long time.
If Skyrim fails to fill the RPG bill, that's just going to open the market up that much more for a true RPG - for an RPG in the grand style, melding modern technology with true roleplaying - deep and complex story and character, with choices and consequences and success and failure, rather than point and click action/adventure sword-swinging and shallow and half-hearted nods to superficial character development, and that game is going to take the gaming community by storm.
It's been a long time since RPG fans have had a game like that, and we're ready for one. If Skyrim isn't that game, something else will be, because the market is there, and it's hungry.