My take is this , Nvidia tried to deliver a knock out blow to ATI with CG and proprietary extensions. They wanted to be in the same relative position Microsoft or Intel is to their competition. Basically the tried to leverage there marketshare a little too early in my opinion and tried to push the industry in a direction that was favorable to them. Alas the R300 proved to be a brick wall and Nvidia broke it self apart on it.
I think some ppl. don't realise how much trouble Nvidia is really in. They are loaded with debt and liabilities. There product line is a flop. As far as optimising DX9 for the FX because of marketshare , keep dreaming. Nvidias marketshare lead can be attributed to the GF4mx which is DX7 . I don't think they will be coding for that. They will code for the most prevalent DX9 compatible hardware which at this point is the r300 series.