I disagree. If the iPhone is going to be a true productivity device, or if Apple wants a prayer at selling to the business market, the iPhone will have to run additional apps. We're not necessarily talking about games. We're talking about MSOffice compatibility, PDF readers, contact management apps, secure storage apps, and databases. These apps will be best developed by 3rd party entities.
Recent stories have emerged indicating that the iPhone platform will not be as restricted as originally thought. The compromise solution to the Limatoones' stability argument, and it's a good point, will probably be an Apple requirement that Apple certify the app as being "iPhone ready," perhaps even marketing it directly through the iTunes store or other download service.
But I for one will have difficulty switching over to the iPhone if my current Treo's data can't effectively be transferred and, preferrably, synchronized.
-K