Nope, as Nintendo will probably launch their next home console during holidays 2011/ early 2012. Wii will probably get "serious" support until then.

After that, very few companies will be willing to support it, even less than the amount supporting it today (lol)

No, but I think competitors will also release new consoles by the same time the super Wii launches, max one year later.

not dominant, but 'around'

I think the Wii has the potential to do it, but it depends if Nintendo want's it and keeps feeding it with interesting games. The same could be said for the DS, it could least 10 years ( I think no one here doubts that), but Nintendo choose to  totally destroy the PSP and expulse it from the handheld market forevis.

Even if it would stay ''dominant'' in the amount of hardware units sold, it won't be in the software department.

Perhaps it could, but we'll never know, as Nintendo will definitely release a new console within the next 5 years. Thus forcing both Sony and Microsoft's hands, too.

I think the Wii Succsessor will come Q4 2012

Technically, the Xbox360 and PS3 together have more market share already, which is important for 3rd party studios.  Both the X360 and PS3 have sales growth, while the Wii is gradually losing sales.  On top of that, both the X360 and PS3 are hefty pieces of hardwar and intended to be expanded upon--so as to broaden their lifespans.  The Wii was outdated before it was released, and cannot be expanded or upgraded.

The Wii was Nintendo's ultra-successful stop-gap.  The successor will be announced at next year's E3, and maybe launched at the end of 2011.  They'll have to in order to remain competitive, to maintain an edge, and to sit logically with the 3DS.

First, you made the mistake of grouping two platforms together, the Xbox 360 and the PS3. Third parties look at each platform individually not collectively. Secondly you miss the fact that Nintendo is enjoying it's best software sales ever on a home console, the Wii. They are not going to give that up just to join a technology race. A race that has not benefitted Sony or Microsoft. Those two companies are pumping a lot of money into their respective consoles this gen without any guarantees of success.

Thirdly, the Wii is still selling very well, with out a big game being released, and is only behind the Xbox 360, which has a new model and clearence sale of old models, in world wide sales. Nintendo is not going to kill off the Wii any time soon. There is just too much money to be made with the hardware and the software.

A third party can build a game for the Xbox360 and port it to the PS (and/or PC) for relatively little cost.  Much cheaper than building said game from scratch to run on the Wii.  The other two are not a "technology race" anymore--nobody cares about the minor differences in architecture of those systems.  They're comparable, and making games multiplatform for those two isn't that hard.  Look at Final Fantasy XIII--the change to put it on both the Xbox360 and PS3 really did not lengthen development time, and no doubt, was financially smart for Square-Enix.  You act like the X360 and PS3 aren't successful.  The X360 is more successful than the original Xbox by a long shot, and the PS3 is a far cry from the GameCube's dismal 3rd place status.  Both companies (MS, Sony) are making tons of money now, and third party companies generally have quite a bit of success there.  This may have changed, but for the bulk of this generation, the X360 had the highest attach rate of any (current gen) system.

I did not "miss" the fact that Nintendo is enjoying its best software sales ever, you just chose to assume that in attempt to one-up me.  Everyone knows the Wii is the most successful Nintendo console ever, and from that, Nintendo's software is selling way better than ever.  That's just numbers.  More available consumers means higher available sales. 

Yes, the Wii is "still" selling well--especially compared to the GameCube at this time.  But it's sales are down year over year while Sony's and Microsoft's are roughly the same if not better--even before the new X360.  Besides that, how many of us still play the Wii and enjoy the motion control, and how many feel that it's grown to be gimmicky? 

I sincerely hope that Nintendo doesn't just kill off the Wii because if they do, they're going to piss off consumers and developers alike.  But the successor will likely be revealed at next year's E3.  It's their current pattern, and it's logical.  It will happen.  Nintendo's trend the last two generations has been to announce and launch a new portable system, then a year later, follow with a new home console.  This will be no different.

EDIT:  Shit, I can't believe I overlooked this:  By your logic, Nintendo wouldn't be "stupid enough" to put out a successor to the DS line at this point, because the DS is still the top selling system in the world.  Releasing successors while the previous system still has some strength in it, and while it's still in the public mindset is a smart way to maintain popularity and interest.  It actually makes more sense to replace the Wii right now over the DS, if all you're going by is hardware and software popularity--the DS still easily tops the Wii in both.