AMD didn't give away the AGP market. Nvidia still haven't announced a DirectX 10 AGP part, but ATI will be ready with its new AGP parts. The good thing is that these cards will support Avivo, all the fancy Video and 3D features and they will work in old motherboards.
There is a future for the AGP upgrade market and some people simply love their Nforce 2 motherboard and socket A CPUs too much to give them up that easy.
RV610, Radeon HD 2400 will also have an AGP version, but we are sure that this version won't be coming out before June, if not even later. We will keep our eyes open.