This is not a sane decision. Any real-world app developer, armed with this information, will pin their development tools to Visual Studio 2010 for the next five to ten years at least.
We can't afford to alienate our customers by breaking our product on XP. So we'll be skipping 2011 until Microsoft figures this one out.
If you want to play chicken with the Microsoft product cycle, you're going to lose.
No offence, but the number of developers dev-ing for Windows XP is such a tiny drop in the ocean compared with Win7 developers that Microsoft would prefer to make VS2012 more awesome for Win7 developers than spend time supporting it on WinXP.