It would be strange if the PS3 and Wii both basically had the same design and were battling it out for consumers (and both had games similar in appear to Wii Sports, Wii Fit, etc).
Scenario 1:
360: ~45 million sold and much stronger Xbox Live as it basically dominates the space that the PS3 and 360 are currently competing in.
PS3/Wii: Both at ~26-28 million as cutthroat competition between the SD twins for casual consumers stops either of them from taking the console lead.
Scenario 2
360: ~35 million sold, slightly in a better position than it is now but due to no HD PS3 it doesn't enjoy as many good multi-platform games. Of course all multi-platform games would look better which could play in its favor as well as being the only system to get many major PC games.
PS3/Wii: Both at 35+ million and enjoying many multi-platform games. Third-party support for the SD twins would be better than what the Wii currently enjoys now.
Scenario 3
360: ~24 million sold as a lack of strong console multi-platform titles for it hurts it significantly.. The system struggles to not be completely left behind by the the "SD twins".
PS3/Wii: Both at ~40 million and climbing fast as a large amount of third-party support ensures both are shoe-ins for 100+ million.
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