IIRC, they have a written (or maybe unwritten) rule that they will not drop support right away. It's probably to encourage adoption of Microsoft's standards and

IIRC, they have a written (or maybe unwritten) rule that they will not drop support right away. It's probably to encourage adoption of Microsoft's standards and software by enterprise. If a major company adopted this and Microsoft gave them a 6 months notice, they'd be pretty upset and less likely to do business with them again.