... How would it play out?  This is my guess:

Sony- The huge industrial empire that borrows from the ideas of many outside sources.  The nation with the ambition to take over the world with little regard of innocents and with a merciless propaganda campaign going against Microsoft.

Microsoft- The defending nation against Sony relying more on the fighting will of its people than technology.  Though the technology wouldn't be quite as reliable as Sony's, and they would be fighting as the underdog on some fronts.

Nintendo- The oriental empire far off from the war, flourishing off of untapped resources the other two forces were unaware of them.  If you asked them about the war, their leaders would be like, "What war?"

Your take?

Nintendo would attack all of Microsoft and Sony's base. Microsoft just ignores it and will be more concentrated on defeating Sony. Sony is trying to defend and build up an army. Right now Nintendo is winning this war.

Sony is with the desire to take over the world and Microsoft is defending?

XD

the other way around, you dummy =P

I'll just compare it to WW2. Microsoft (Nazi Germany)... attacking Sony (USSR)... the fighting is extremely costly and brutal, and Sony losses are extremely high.
While Nintendo (USA) is watching from afar and waiting to join in for the killer blow.

Sega (England) - giving lots of exclusive support to Sony and Nintendo... i.e Madworld, The Conduit, Yakuza 3, VC. There is no exlusive support for MS.

Countries conquered by Germany - lost Sony exclusives. Countries liberated by the USSR - exclusives becoming multiplat.