Here's where I think a happy medium could easily be met. I think 90% of the iPhone apps could be written in web languages and work fine, these apps could be apps that apple would allow to run in the background. Apps that require native languages, like 3D games or simulators, would run by themselves one at a time.
I'd imagine Apple will talk about this. The future using Sproutcore and HTML 5 for example for simpler apps that could run in the background seems to be good, due to a lower overhead potentially.