As for my take on things, I don't think you're evil at all for dropping the older GPUs off the list. Can't support the stuff forever and your profits for them have long since past unless someone's using them like they used RagePRO's in server type hardware or an embedded design with a process shrink applied to the design. If there's some nuance to driving the things right (i.e. the AGP to PCI-E bridge that drove some of the last of the AGP specific cards with the more modern chips...) it'd be nice to get help on THAT particular piece from AMD.
But past that, I'm thinking we're doing decently on supporting the older stuff ourselves with Gallium3D bringing most of the speed back to it all when it gets here.