I can make a stab at predicting the market's direction, but understand that it's necessarily vague. Nintendo's actions to defend their Blue Ocean will vary according to the actions of incumbents (existing players in the market) and newcomers alike.
One thing I'm sure of is that the Wii itself is going to be their workhorse for as long as they can manage it. There's evidence of this already: Wii Zapper, Wii Wheel, Balance Board, and MotionPlus are all upgrades to the same values that the Wii embraces interface-wise. They're beating the competition to the punch on out-innovating them, and basically taking the sustaining value innovations as far as possible before any competitors even appear for those same values. A very sneaky tactic, but an effective one.
What the incumbents do will vary. Microsoft has already started their counterattack with rumors of a Wiimote knock-off for the 360. At this point, it remains vapor and acts only as a limitus test to see how much interest they can generate. That's standard MS tactics; they don't make it unless they think it's worth it, especially when a rumor will suffice. Really, it's economical, but they risk falling behind the new value curves since Nintendo keeps pushing the value requirements higher with Wii add-ons.
Sony's response so far has been to keep on with their original plan for the PS3. That's not a smart thing to do in a shifting market, though; it tends to lead the incumbents who do that to leave the market. I doubt it will kill Sony if they continue the way they are, but it won't be kind to them either.
Eventually, somebody will try to compete with the Wii's new values. When that happens, you can be certain Nintendo will respond with a strengthening of the Wii's appeal to the new audiences. Since the value challenger will likely be targeting the old market that took up the Wii's values, we might even see a slight shift of core gamers to the Wii's same-value competitor. But most of the Wii's userbase will stick with the Wii, due to the elusive brand loyalty (which, incidentally, tends to be much stronger for Blue Ocean products).
At the end of the cycle (I'd guess it'll be a short one; the market is too volatile for the full 15 years of Blue Ocean-inspired brand loyalty to last), Nintendo has made it perfectly clear that they're going to disrupt again and start another Blue Ocean. So you can expect this whole mess to start again around 2015 or so. Only this time, it will be the newer pro-Wii hardcore that will be raising the most hell about whatever Nintendo comes up with next.
Edit: I should note that this all only applies if nobody successfully disrupts the market with a new-value product before the end of the Wii's cycle. If that happens, we'll see a restart much earlier in favor of whomever disrupted Nintendo.
Sky Render - Sanity is for the weak.