Horizon/Spektrum has repeatedly stated that they will not be doing Spektrum modules for aircraft use, for any radio system including JR.
I have always felt this was a very shortsighted postion, but with some of the new features of the DX-7, it is now much harder to module the system for older radio use. The new DX-7 has done away with PPM encoding on the TX and sends direct digital from the sticks to the DX-7 tx rf unit to the DX-7 RX, speeding up the link.
If they modulize the DX-7, they would have to add a PPM or PCM translator to the front end of the module, which does slow things down a little bit more...
Some people have converted DX-6 tx boards to work with the 9303, Hitec and Futaba module systems. There is a thread over on R/C groups in the DIY electronics section if you care to research it. To be fair to Hitec/Spektrum, this is probably not the forum to duscuss the details of those conversions.
Untill someone else rolls out a 2.4 gHz module solution, the XtremeLink module system that is close to being released is the only game in town.
http://www.xtremepowersystems.net