Those customers will find that Microsoft products are not working for them anymore.
Visual Studio 2010 does not work on XP
Do you see a pattern?
I'll have to correct you on that line. VS2010 does run on WinXP because that's what I'm using here.
Btw, VS team have to drop support for older systems. Supporting 3 old(WinXP + Vista + Win7) + 2 new (Win8 + next version of Windows) would have made their support matrix too complex. It's wise to reduce it by dropping systems that no longer in mainstream support.