I'm sure Microsoft will learn from the mistakes they made with Vista. They simply cannot afford to have another disaster OS.
As bad as Vista is you know Gates wants to get 7 out as soon as possible. At least I would if I was him. Now that said, if it does come out next year then I have a hard time believing that it will be polished at launch. I mean if they rush it just because of the Vista problems then it probably isn't going to be any better than Vista, will probably have a lot of bugs and will just result in a lot more complaining from consumers. I think it would be better if they don't rush 7, take as much time as they need with it and make sure it's polished at launch. They don't need another blunder like they had with Vista.