I think you expect too big efforts from Sony and Microsoft, against Nintendo.
If they would truly prepare to fight for that audience, "until their last breath", and stop Nintendo at all costs, we would have seen all their games that were announced at this E3, to be developed for their motion controllers.
In my opinion, they seem to be more like "experiments". One of the possible ways to expand. If the first attempts won't be that successful, they still have the other option, to take refuge in the hardcore audience.
On the other hand, Nintendo is now fully motion-based. They have one way the go. Make it better.
Even if thy wouldn't be aware of the disruption process, they would instinctively to seek for options to improve their current values, to upstream their customers. But they are very much aware of it, they based the entire Wii strategy around Christensen's books, (you don't even have to believe that it works, the fact that THEY believe is enough to predict their behavior), and they will very consciously fight against Sony and Microsoft.
In the previous years, they earned ~10 billion dollars of profit, and they can spend a big part of it on fighting for that market. (that fight might expand to the next gen). The Big Two has even more money, but it is very questionable if their higher executives are ready to spend all of it on that part of the market where Nintendo is already established, and more profitable. The Playstation brand, for example, is admittedly in "survival mode".
I can clearly see them abandoning the "motion control war" if it is not profitable soon enough, but I don't see Nintendo abandoning it after 1-2 failures.
