My personal opinion is we will see new iPhones in June, but they will be minor refreshes, ie. more memory, better camera, video, longer lasting battery and styling changes with perhaps some additional colors.
I do not expect a "premium" model like an iPhone HD or any really big changes that would impact compatibility with existing apps.
Main reason is the economy. A premium model could make sense if the sales potential was there and they could price it to keep margins high. But in this economy, no dice. I do believe they have good prototypes, but the decision to release the product has as much or more to do with the market conditions as it does the technology.
Second reason is the current iPhone specs are still industry-leading in many ways. The strongest competition (G1 and Pre) will still be in their infancy when June rolls around.
I also believe we'll see a big firmware bump for existing iPhones at the same time, perhaps version 3.0. It might be charged for. It could have features like:
- Advanced touch gestures for greater OS control and shortcuts
- Cut and paste (using the advanced gestures)
- Improvements to Exchange support (create meeting invites, todo list, colored categories, etc.)
- Speed improvements
- True multitasking for certain 3rd party apps (as an alternative to the Push Notifications approach which I'm starting to believe they shelved)
- More bluetooth features
That's my opinion. Let's see what happens eh?