Well, first of all, I belive Vettel is driving 100% one day for Ferrari (He even speaks italian). The question is when. Alonso is staying until the end of 2012, and if he becomes champion, then I belive he is going to stay longer. Rumors says, Massa is extending his contract until 2013. I don't really belive Massa is going to be Champion this year or in the near future. He had his chance in 2008. That was his year, but lost it to Hamilton. So maybe Vettel is going to replace Massa...?
I like the Ferrari team (who doesn't???), but I too like the RedBull team among others. But still I would love to see a racing driver wining several WDC without having to drive the historic top three winning cars: Ferrari, McLaren and Williams; in his whole career. The last one to do so (among five other dirvers) was Jackie Stewart.
So, I belive Vettel has the potential to win the WDC several time. And I'd love if he did so in other cars than the top 3 mentioned above.
Your reasoning makes sense, ie in the sense of having WDC/WCC from more teams than the traditional ones... of course it would be nice to have a champion in a 'new' team or from the new age of F1. BUT i do believe that there are some teams REB BULL included that are merely comercial adventures rather than real racing teams. Not to downplay their personnel or their abilities to make a winning team/car... but i think teams like Mclaren, Williams and Ferrari are in it 100% for the racing. Others, such as Toyota and Red Bull i think are in for the comercial exposure.
In the end, i dont really mind which team/driver wins the championships as long as the competition was fair. For example, I was not too happy with Brawn winning last yr because i think the championship was decided in a Fia hearing (ie allowing or not the diffuser) rather than on track, ie as Lewis and Kimi got it before.
Vettel to replace Massa?? maybe, probably. He has mentioned he likes Ferrari, but i think he will go to the best offer and the best possibility to win. And offers he will get plenty.
Vettel to win a WDC?? definitely. Perhaps not even this yr; but just like everyone knew Lewis would win one... Vettel will win at least one.
Came out fighting indeed.