Nothing was announced about "lan" controller multiplayer yet, who knows, maybe we'll get it.
SO far there is no mock up with more than one tablet, wait and see, but the wind show the wrong direction right now
Price is not defined yet, they just said it's going to cost more than the Wii (the cheapest PS3 is still 299, WiiU could end up costing that) and we don't know the exact power of the thing, from the tech demo they've showed it looks like the difference is quite significant.
More than the wii is already too much, Xbox is way cheaper and more mature.
I didn't find the tech demo impressive, it look like it's principally texture but not much more anything else. Also with megatexture and looming voxel engine, or the simple optimization of relief mapping, all console are likely to make a huge bump in details without munch hardware requirement.
THQ, Namco and Ubisoft announced they are working on exclusive titles for the thing, as for Nintendo, Smash Bros and Pikmin were "announced", the system launch window is "April/2012 to December/2012", they're probably waiting for a better definition to announce stuff.
Waiting to see something, smelling mass port. Also pikmin is likely to be a repurposed wii game like Zelda twilight. They had confirm that dev on smash bros has not yet start (sakurai goes so far it's too early to announce that) and it's not a game that takes 1 year to make, sakurai did not even finished Kid Icarus yet.
iOS and Onlive can't do all the stuff this does, for once they don't have buttons! PSVita with the PS3 could though.
Button is more like convinience, but the streaming and multiscreen part is there, Onlive sell a "universal" controller too to complement his service. They have gyro and they have camera, and touch is multi. It's not exactly the same but it enough of a variant (unless Lan multi is confirm).
Summing up, I don't think we have enough information to go judging it's success yet.
You are right, it's speculation but yet not unfounded. Let say it's a big bad Worry.