One big problem with your vision is that you either leave people with a tiny 10 inch display on the desktop or a huge (26" in my case) tablet to lug around. And if you're doing the kind of gaming where you need more horsepower, you aren't going to want to do it on a tiny screen either.
Yep point taken, I thought about it more just after posting but there's still a scenario where the horsepower and big screen could be inside a large TV/game console unit but when you'd attach the tablet device it could take over the those systems just acting as a HDD+OS. With the "usual quality level" of the displays PC makers use I think it would be a flop given what we know OEMs+MS have come up with in the past. That's why I said it has to have superb display, something better than anything the buyer has seen before. The finger input+PC extensibility features are just to seal the deal.
I recently saw the XEL-1 OLED display in person and would have no doubt that mere casual users of PC apps would be entirely satisfied with that as their primary display even it if it's just 11" (assuming it also had higher resolution than it now does). First time I returned twice to the shop just to stare whatever they had running on it.