I've just been looking at YouOS and Goowy, two of the latest, free, online personal OS offerings. YouOS, in particular, has come a long way in the year since I last looked at it.
Which leads me to conclude that the next mainstream OS will not be desktop-based. It will be hosted by central servers. Consumers' security concerns can be alleviated by tight integration with keyfobs, and possibly a light, encrypted local instance of the OS running on linux (maybe even on the keyfob).
The enterprise OS is a different story: the winner there will not necessarily be the most technologically advanced, but just the one who wins the skillset wars.
Where are the tech dev skills? Somebody give me a Google Earth overlay of tech dev skills: geography and skill type. That will lead to the next paradigm.