lol so they are d00mzed already? :D it all comes down to the games...not like ms and sony are stopping making their other games and just make Move/Natal games or anything...if anything it will be a valuable addition + push for them given they get some good software to back it up

I see natal as being huge, once implemented in xbox 360s and PCs. Yes, what others have said, Move and Natal will just extend the longetivity of the two consoles, but in extending the life of the console it will also extend sales.

Wii is old tech, so why shouldn't people move on to better tech? Will there be a hit in the Wii sales ( and i mean wii sales lowering)....yes. Natal is going to be epic! (I cannot speak for Move)

In conclusion I do not think that Move and Natal will fail.

@OP:
They'll help MS and Sony to avoid that Nintendo's lead furtherly widens, maybe even partially fill the gap, but it won't change the current situation where Sony and MS this gen can only fight for 2nd place. Not a failure, if their true expectations are realistic, but not even a memorable victory, if they succeed. Anyhow, they must try and at least limit the damages, they cannot be left so much behind anymore. The best Sony and MS can probably achieve is that this gen Nintendo ends 1st with ~40-45% and they end around 30% each, with little difference between each other. I'm meaning WW, MS will still keep a strong lead on Sony in USA and Sony a strong lead on MS in Japan and a smaller one in EU.

After seeing Sony software for the Move and considering how lame 3rd parties for the most part were on Wii with motion-controlled big sellers in the past 4 years, I agree that it'll fail to give long-term hardware boost for PS3 (unless Sony has smth up it's sleeve on E3 for Move). Natal though remains to be seen, since I didn't see anything except for, well, you know, Ricochet and some other game.

We know so very little about Natal and Move right now.
I think it's very precarious to talk about them.
Let's wait for E3 and then you can forge an accurate opinion.

All I can personally say, is to look at history, because it usually repeats itself.

When was the last time and add-on to a console, especially 3+ years into it's life, caused a resurgence in Hardware sales?

Natal I feel will be more successful than Move but will be hampered by technical problems. Often times, projects that are overambitious (Robotech Crystal, Freak Boy) are just limited by the talents of the artists and the hardware of their times.

Move will be just as effective on revitalizing PS3 hardware sales, as PS Home & LittleBigPlanet were. However, I get the feeling its true impact will be blurred by projections, bundling with software, and/or a price drop at the same time of its release.

Both are trying to be something that they are not.

It all depends on software. And right now for that, Move's looking outdated and Natal's a big question mark.

natal is gonna be bundled with arcade for $299...
they should have just made Natal an Xbox 360 successor instead of an addon 0.o

Move, as we can see, shows a huge quality, especially in precision.
Natal is a question mark. We know how it works, but still... few informations right now.

However, there are those feelings about Move being underused bucause of Wii and Natal promissing a huge event because of its technology. And we can't expect how people will react! Not even point problems or flaws because we haven't seen their softwares yet!

After E3 we can really understand a bit more of Natal

I completely agree with you on that one.  They should have released it for next gen with better graphics (also would have had time to work out the extra bugs). I personally believe it would have had far greater potential and might have gave M$ an upper edge in the next gen console race.