Tanaka said in an interview that he had in mind/wished to upgrade the engine to work with dx10~11 at some point while he was still in charge, but now that he is now only god knows if it will happen. And seriously right now there are more important matters to deal with than tweaking the engine to run on dx10~11 with all the glitches it can add to the already omgtoomanyglitches.
But, yes, once the PS3 release is out and most of the biggest problems are fixed, it would be nice to be able benefit of the new dx wonders.