Existing PS360 gamers have a software library baggage. Nintendo need to attract new core gamers or existing fans first. Those "graduating" out of DSs would be perfect.
You mean those graduating out of Wii would be perfect. There's 80 million of them, after all. More importantly, their games, balance boards and wii-mote+ controllers all carry over.
The advantage in similarities to the DS are more conceptually: there is a similarity between the DS and 3DS and the Wii-U setup that your main living-room TV will never have a direct touch interface, so the second screen can fill in that gap very similarly. All the solutions and ideas found for that setup for the DS and 3DS can be reused and expanded upon for Wii U. In that respect I think the setup may almost be more interesting for those (few) who do not yet have a DS or 3DS.
As for the power of the machine, it is early days. I think that the final machine will be more powerful than the 360 and the PS3, and have 1GB of RAM instead of 512MB (Assassin's Creed developers suggested as much). The main question will be how much work it is to extract the same kind of performance out of the machine versus the 360 and PS3's more optimised engines.
Even if the Wii U becomes the most powerful of the three for a (little?) while in terms of graphics, then the next question is at least for multi-platform titles, what the advantages of the controls are going to be, if any. The Wii U controller (I'd like to call it WuCon from here on
) doesn't immediately convince me as a comfortable replacement for a smaller, lighter regular dual shock type controller. The analog sticks are the same type as on the 3DS, which I think are a big improvement over the analog nub of the original PSP, but I have a feeling that if you were to rank them, the order would be: analog nub < 3DS / WuCon disc thing < Vita's smaller Analog Stick < regular Analog Stick. So that means you may end up having a regular analog stick controller from the Wii (with the GameCube ones seemingly no longer supported), the Wii-Mote and Nunchuck combo, and the WuCon. That's getting really cluttered. And for multi-player games, things get even more confusing.
This means that unless a multi-platform game is going to make good use of the WuCon or at the very least a great implementation of the Wii-Motion+ controller / Nunchuck combo (with a tiny concern on relative accuracy decrease with HD displays, but it's probably fine), things could get pretty complicated. But they need to get it right almost immediately at launch, because I'd wager at most 3 years before a next-gen system is launched.
In addition, that completely leaves out the PSN and Xbox Live services. We have no idea yet whether Nintendo willl bring its service up to speed in that area, and for existing gamers it will not be easy to switch.
But those 80 million existing Wii owners are going to be the primary target, and the way to convince them is going to be similar to how Wii owners have been convinced before: by offering a unique experience, and with the advantage of keeping existing hardware, software and unique Nintendo brands.
Of course there is a tonne more to say, but it will be ever so increasingly interesting to see where the market will go from here.
