Serious question.

Power and price being equal.

logic suggests the same would happen

Uncharted and CoD would have sold the same in SD and that wouldn't have any impact on X360 sales.

Interesting.

Personally, I think if Nintendo would have made a BluRay player, HD-DVD would have won that particular format war.

Logic suggests things would have played out quite differently, since Sony and Nintendo would have made different games. Neither the PS3 as a Wii nor the Wii as a PS3 would have sold as well if made by the other company, because the PS3 and Wii both played to their respective companies strengths. The 360 likely would have won the generation by a small margin, but the gaming industry as a whole wouldn't have seen the growth that it did. Rather than 260+ million consoles being sold, I'd say it probably would've ended near 180 million. The handheld market might have even suffered a bit as well, since the Sony and Nintendo brands would be weaker.

I daresay X360 would have won the war.

The Wii itself, not necessarily Nintendo is why I disliked the Wii. I have almost no interest in 1st party games from either camp. A SONY Wii, a horribly underpowered console, with clunky (imo) motion controls as the primary input device. Third party multi-plat RPGs, the games that I buy, would be inferior to the versions on the X360. So I would not have bought heavily into a SONY Wii.

Likewise a Nintendo PS3 (sic) would probably have had the same problems the Nintendo Wii did. Almost zero RPGs. The Wii had Xenoblade chronicles, really what else? I doubt they would have had much more given Nintendos track record with 3rd party studios. Lack of good 3rd party RPGs, a complete lack of synergy with how Nintendo does things. So I would not have bought heavily into a Nintendo PS3. 

Thus the choice would have been largly in X360s favor by default.

Keep in mind I ended up owning all three consoles. My PS3 library is significantly greater than the other two though.

100M 360

40M SonyWii

30M NintyS3

ish?

As an owner of all 3, what % crossover do you think there was last gen?

You remember gen 6 right?? Well this time the mighty Xbox 360 takes the PS2's crown.
Sony showed they are terrible with the casual/family crowd so the Sony Wii would flop. Nintendo would be left with the GCN2... like they are now and everyone would have bought the 360, the console with all the popular 3rd party support.

I was thinking more like

75 360

50 Sony

55 Ninty

Because all three would have suffered. Sony would NOT have done well with a Wii type device. Nintendo would only have done that well due to Sony's failings creating more room, while the 360 would have benefitted more from its head start, but ultimately wouldn't have benefitted from other factors. Whether you like the Kinect or not, it definitely helped sell 360s (over 20 million Kinects sold to date), and wouldn't have been made if not for the Wii. With both Ninty and Sony suffering, there would be less interest in games overall, and that would also make the market smaller.

If it went down as OP described:

1. HD graphic wars would not exist.
2. It would have sold 300million instead of barely 100million because it would have had 3rd party support.
3. Motion controls would have been accepted by hardcore gamers because Sony did it.