ok this is strictly from user’s point of view. Firstly who knows what is hidden under the hood…what code they were and are using borrowed or not? I’m not sure they would want others to know.
As far as i understood with my limited knowledge of how a OS works windows uses the registry right? Not sure if this rly is the case but i was told that the registry is partly why it is so slow…so abandoning that would be maybe a good idea no? The OS has it’s faults but they can be ironed out with some drastic changes IMHO.
Going with this i strongly believe that in order for microsoft to make money in the future they will have to abandon certain parts of their OS…go with a UNIX-BSD type kernel and their own desktop (that Aero windows thing) and open source both…or not if they go with BSD style licensed and closed source only. When this is done whether they choose to ask money for windoz or not is their business, but they can surely market the “addon” programs (like Microsoft Office) better if windows behaves more like the other UNIX type OSes. Immunity to vast array of viruses can be achieved all they have to do is abandon their current OS and slap on their own desktop allow for root make every program compatible with the new os and enable interoperability of the microsoft programs with other OSes…blah blah blah.
Due to their prior marketing and known name in the general publics eye i honestly think this move would land them a heap of cash.
Windoz sux as a server? and now as a desktop? No prob…abandon, allow microsoft closed source to run on GNU/Linux, BSD and other Unix systems, let’s sell our better marketed software. <–is what i think is in their minds…or something sinister and cruel rotfl! (ok ok
fooling)
It’s hard to compete with BSD and GNU/Linux, they r more stable, faster and the os itself or at least the software u run on it can be 100% free (as in free beer) and open.
IMO what M$ has going for itself now is not Windows but the programs that run on windows itself. Windoz is dead and it most likely will not rise from it’s grave but fall further and rot.
Another thing they have going for them and i believe it is why windoz is still in use on the desktop are the video games. Games like Mass effect, Crysis, Prototype, Jade Empire, Fallout 3, Oblivion etc…
You may say wine can run those games too. Well yeah but nothing runs them soo smoothly as windoz itself!
How many of us still use Xp or 7 just for games? I know i have a pc set up for my brother with 7 just for the games. He refuses to touch GNU/Linux for 1 reason alone: “games don’t run or run wih lower fps on GNU/Linux”. The biggest battle imo is to bring games to run on all operating systems and not just Windoz with it’s directX.
As i see it there is a possibility M$ will go with and open source, possibly free (not likely free as in free beer dough) OS integrating the good parts of windoz as base platform for their other products which will most likely remain closed source. They can’t pay off hardware manufacturers and distributors for much longer and burden them with shipping a very costly and crappy OS any longer 
Either way it’s all good for us. It will mean choice. We’ll have closed and open quality programs to choose from as users, dough i doub’t i’ll use the commercial closed variant. Companies may do however.