ATI are rushing its R520, so I doubt it would outperform what Nvidia will bring out next.
the FX-5200 was not a "complete waste" of a card, it is a very good card for those who don't have much money. I've seen it run Doom 3 okay.
I'd say the reason the 5800 was pulled out is because it wasn't selling very well. the FX's were by far not a "failiure" but ATI did have the lead in this generation.
ATI had the lead for quite a while, but now it's Nvidia's turn.
the X850 pretty much is an X800 "on steroids" and so is the X800 to the 9800. however the 6800 is a completely new card against the FX's
the X850 may be "better" than the X800, but against the 6800 the comparision is different. the X800's do not give so great OpenGL performance over the 6800's, but give similar Direct3D performance. the X850's are a similar card to the X800 and give similar performance in OpenGL and Direct3D. the 6800's still win in OpenGL, and often in Direct3D too.