Really, I don't care what the real reason is for XP's prolonged life.
All that concerns me is the fact that it HAS been prolonged and Microsoft has failed to manage it into an end of life scenario.
The fact still remains that a quarter of all machines in North America are running XP. Developers are now faced with the choice of lost customers or higher development and support costs.
Because Microsoft failed to manage THEIR platform's lifespan they are going to just make developers cope with the pain of their failure.