That is quite an ambitious point :) I noticed that your observation of Vista has some striking similarities with Sharepoint. As much as i like the neat functionalities of a properly maintained sharepoint site, there is a HUGE learning curve for end users. We are experiencing this at the moment: the biggest drawback of sharepoint is that it forces the user to adjust to its structures instead of building on established workflows. So from the end user point of view i doubt the feasibility of a sharepoint OS.