Very interesting interview !.I think that Dx10 is a pretty hyped up API and Dx9 definetly was a big leap.Even idtech5
is based on Dx9,but having said that,I feel APIs are still going to stay around and not just die down..atleast not in the near future..if the APIs stay,so will probably the hardware too(and continue to evolve with better and better features...probably GPGPUs will overtake the CPU/GPU market)
There is too much of legacy code and not to mention years of effort to create powerful and optimised APIs..so I guess they will stay and evolve and be widely used.