I agree with PedrosPad and The Bat... X360 extensions for current coding environment, and a semi-emulator to run this on a PC for testing before MS certification. It'd be cool if it included a wired controller too
No where does the definition of a developers kits state that you have to be able to run your code on the actual hardware.
I love how everyone automatically applies this to homebrew and "MS will limit our abilities" blah blah blah... as if they were going to somehow give us a way to test this stuff on a retail console.
They can give use fully functional software for $100 without worrying about big name devs feeling cheaped out because big name devs got development hardware to test their own builds... THATS the limitation.
Innovative games are a dying breed in today gaming industry, if you make it easier for indy devs to get into the game you open the door to a whole lot more innovation. Which means more game sales (and $$ through MS licensing) and thus more consoles sales which means more game sales, etc, etc, etc...
I'm not the greatest programmer in the world but I've got visual studio and if I can snag a kit for $100 that comes with the appropriate extensions and some kind of emulation layer for testing, I'm all over that like a hobo on a ham sandwich.
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If you DO want to apply this to homebrew then it DOES help that too
On the Xbox 1 the bios images are illegal because they're based off of MS's own bioses and thus pirated software. We also can't distribute XBEs because our homebrew stuff can only be compiled with rogue XDKs (again pirated) making their compiled results also considered pirated/illegal.
If the XDKs can be had for $100 that means the homebrew apps, which might never be distributed or authorized by MS would potentially be freely distributed in compiled form since we would be able to compile them with actual licensed XDKs. To run them the console would still need to be modified to run unsigned code. However if we were to determine a legal method of doing that (legal bios/firmware/what have you) then it would completely legitimize 360 homebrew.
Not to mention the XNA can supposedly be used to make Xbox 1 titles, which means... we could potentially see a legal XBE for XBMC if this kit delivers what it's supposed to.
All that aside, we don't know what kind of legal restrictions or agreements you might be required to sign to get one of these XDKs... but I can't see this being anything more then an overall good for the industry and Xbox enthusiasts.