ET3D: Smartphones are probably around the level of the HTPC and 360, and much more powerful than the Wii.
I'm surprised if they really are that powerful already. Or then the 360 wasn't that powerful to begin with. I was always thinking current smartphones are maybe past PS2 power at the moment (judging by how the most advanced Android 3D games look), but that was merely a guess.
Part of the problem may also be the storage size. Seeing how humongous games have become (outside of indies and strictly mobile games), smartphones have the issue with local storage. Dunno if there are new technologies coming where you can have hundreds of gigabytes or even terabytes of low-power storage on a tiny card... (I saw some demonstration from Intel about that a couple of months ago, the next step from SSDs). Another option might be streaming games (making storage size irrelevant), but they have issues of their own, like the requirement for a reliable non-capped and high bandwidth internet.
Also, to benefit from using your phone as a dockable gaming device, I guess there should be some benefit in being able to detach it from the gaming station. Ie., the games should be so that they work nicely both on a smaller touch screen so that you can still play them away from your home/docking station, and on the big TV (possibly with a controller).
I don't know if there is real demand for such. My wife plays Candy Crush often on her phone. I've sometimes asked why doesn't she play it on the tablet instead with a bigger screen, but she rather just plays it on the phone. Would she be interested in putting her phone on a docking station in the living room to play Candy Crush on the TV? Most probably not, she seems to be drawn specifically to mobile gaming because it is mobile, and more personal/private.
It may also be that mobile gaming is considered more personal. You don't share it with others on the big screen, you play it on your small device in your room or cuddled in the sofa. This is a bit like how internet and social media have become more personal, people wouldn't like to read and write their Facebook entries on the big screen with everyone watching. I get a laugh of those early 90s projections how in the future (=now) people will make video calls from a big wall TV in their living room, or browse internet from it. It went to exact opposite direction, people doing those things with their small devices that they carry with them all the time in their own privacy.