Srsly? 15-20 year? I think Windows will be dead in 7-10 years. It shouldn't still be alive today. Windows is an OS for physical media. It wasn't built for networking and security. Windows'core needs to be scraped and MS needs to come up with something fresh from the bottom up.
Actually, they don't need to do anything. Others have already. MS just needs to bow out. You can't be on top forever.
Could someone PLEEEEAAASE tell me what makes 7 better than Vista? Please??!!! The taskbar is changed to icons and there is a preview for each one. That's really about it. The interface is still a mess with menubars hidden sometimes and not others, there are still several hundred control panels, and the system is still based on DLLs and a registry. Network navigation is a total joke. Built in media viewing is not even a joke. And, yes, I've used 7 quite a bit for my gaming needs so I know what a turd it still is.
It's a fundamentally confusing, unsafe, and bloated OS with the slightest amount of polish added.
Actually, they don't need to do anything. Others have already. MS just needs to bow out. You can't be on top forever.