Its not like the world will end when they end support. The OS will work the same as it ever has.
Id say it will be VERY likely there will still be 10s of millions of XP machines running another decade from now.
If you are using business oriented software and not playing games, there really is no need to upgrade. Upgrading just because something is old, is dumb.
Especially when what they are currently offering is the disaster that is windows 8. Buy new hardware with windows7 instead of xp, sure. But upgrade just to upgrade, waste of time/money/resources. (again we are talking about non gamer, or power user who needs modern hardware, we are talking about writing documents, etc.)