In a nutshell, with taking jtags and rgh online, microsoft pretty much stopped caring about 360 modding I would say
It doesn't matter what they really do,since we own "devkits" too
In the end it's discontinued, so hacking it, is really the only real aftermarket support, we know enough about it to take a (phat) mobo, swap the cpu, jtag into xell, either use libxenon (possible but nobody that knows will tell how to do this properly) to set fuses or boot an XDK recovery
The winchester was pretty much a lowkey fuck you, I feel it was done simply to say yeah it is "patchable"