im am sure a few 3rd party coperations have things in the works. their is an adapter due out for the headset.
i am sure mad katz will have a aftermarket controller,and that jazz. gamestops after glow seies will proably continue. but it wont happen till the console is out.
microsoft gets first shot at the 2nd-4th controller sales and add ons stuff.
its not like the 3rd party stuff is all that great. the oem units tend to be the best fit/finish with the components.. the delay or feedback on the 3rd party is usually a bit behind.