Most likely not, They are working on Natal and will be quite busy. I don't even think a Slim 360 will even be made...............
And like ^ said, A smaller case means more heat consumption, the Ps3 slim is about the same size as the 360 so thats why they could safety make a slim in the first place.
Probably not. The Jasper was supposed to produce a lot less heat, so in the fat shape, the RRoD or overheating shouldn't happen, but it still does. So if MS puts the Jasper chipset into a tinier case, the smaller space will only heat up faster.