Maybe in that scenario an alliance with Microsoft would be beneficial to both parties.
I don't know if MS really has their heart in this XBox thing after this cycle, and that way Nintendo could basically make the hardware and still operate as they currently do, just with MS' backing.
I think what MS really basically wants is just their OS on the device ... so let them have it.
Honestly back in 2000 Nintendo should've just agreed to allow Windows or some watered down form of it like the Dreamcast had rather than having to deal with two conglomerate competitors. It was just never a really good situation for Nintendo to get themselves into. Basically they bet the farm on MS failing out right, but they didn't, and they got stuck into a three horse race that they wanted no part of.