Actually, Win7 SP 1 mainstream support ends in Jan 2015, while its extended support ends in Jan 2020.
http://windows.microsoft.com/en-us/w...ucts/lifecycle
I sincerely doubt that anyone will be using Win7 in 2050 - it's just not that perfect a product to overcome what will surely be leaps in technology by that point in time.
http://www.youtube.com/watch?v=hShY6xZWVGE