Perhaps (and I do stress perhaps) the next generation iMac, will be an iPad with Mac OSX on it and the internal guts of a MacBook Air. This way he can have tons of haters and free press about the iPad and its lack of user freedom and control. This is the kind of press money simply can't buy. Imagine an entire internet up in arms about the denying of iPad apps, raging madness from some about the closedness of the platform, only to then turn around and say a year from now... "we listened and here is the new iMac". Everybody in elation goes out and buys an iMac in much greater numbers than if he did it the straight forward way as more people than ever were aware.
Jobs isn't stupid. He knows that tablets, laptops, and portability at large is the future of personal computing. By limiting Apple to a closed solution like the iPad, he is simply waiting for some good competitor (google?) to come along and blast them out of the water. (and they will eventually, it is only a matter of time). He won't let that happen, so I think he will provide both closed and open solutions. The only question is when?
Of course, the opposite argument is that a closed solution that you control entirely is what all capitalists salivate over. In general, control like this equals money. If he can pull this off, and do it while keeping everybody happy, then Apple will be absolute. de facto. save a few small-time competitors which take up the other 15% of the market. I don't really like this however.
I would like to hope that a computer revolution birthed in openness and freedom will stay free and open.