Windows XP isn't going anywhere. I guess that it has a market share of more than 70% in the large corporate market and this isn't going to change in the next couple of years.
If you pay enough money you can continue to install new versions of XP. If more than 50% of PCs are running on XP then I can't see how Microsoft can discontinue support.
The real problem is that none of the subsequent Windows version offer anything more than XP