However the problem with Dashboaord wouldn't be improved by running iOS apps. For many of us Dashboard never really fit our work flow and methods. Regular Mac apps just are far more convient especially if you have a large sceen or multiple screens.
The problem here is that a full OS/X app with touch support would be much better. You could get the best of both worlds. Still the ergonomics of a touch screen on a laptop is a huge problem.
There are a number of ways for Apple to address this though. One idea floating through my head is a transparent laptop screen that is viewable as a standard screen when oPen and as a touch panel when closed. Actually the screen needs not to be transparent if you use two LCD screens. In this approach OLED might work better. From Apples standpoint it shouldn't be a big deal software wise as all they would have to do is reverse the image. The neat thing is the utility of the machine would increase drastically but remain mechanically robust relative to other convertibles.
This has been mentioned again and again but XCode already does this. Every app built for the simulator is an x86 app. The fact is you can easily run iOS apps on a Mac today if you have the source code. I don't see Apple going public with this technique though as it isn't a clean way to bring touch to the Mac.
There are two problems here. One is that dashboard isn't a solution to any pressing problem on the Mac. The other problem is the age old issue of making money off you works.
App store is a tremendous motivator for even minor app developers. Even modest pay backs to developers can result in numerous apps being produced that wouldn't be other wise. Like it or not the locked down nature of iOS and the low impact app store has lead to a very positive platform for developers.
This is one reason why I would like to see an app store come to the Mac. We obviously don't need a locked down platform but a secure and low cost way to distribute apps would be very helpful. Such a facility would lead to Mac's software library tripleing very quickly.
A good thought but honestly I don't see Apple going this route. They will bring touch to the Mac when it is ready. Adding iOS apps to dashboard would be a bust in my mind. To get the functionality of these Mini apps on a Mac requires giving developers an incentive via a framework for profits. Or atleast cheap distribution of their works.
Regarding the payment model: I mean that an IOS dashboard model would use the SAME pay app your buy in the App Store now. Perhaps actually incorporating the sore into the Dashboard.
Your technical points are interesting. I tend to disagree with the idea that Apple's existing method of compiling for x86 in xCode for testing isn't how Apple would do this. It is exactly how they handled the transition from PowerPC to x86. Universal App Binaries would hardly be unprecedented.