yeah..... well i want a pony.
sorry, couldn't resist. I just don't think it's going to happen. MAYBE we'll get .22LR down the line. if anything, i think you'll see a 9mm conversion like for the .40 and .357sig XDs.
at this point, it'll be up to aftermarket companies like bar-sto and EFK. springfield/croats are too busy keeping up w/ production of .45 and maybe working on subcompact development. also, getting the .40 caliber in the .45 frame w/ 15+ rounds would a big LEO draw. hell... a 9mm w/ 20+ capacity wouldn't be anything to shake a stick at, either.
i'm just guessing here but i'm betting that's where there priorties are.