Yeah probably ApplePhone...sadly. But remember the launch of the Apple TV? It was going to be called the iTV, and Steve/Phil actually called it that by accident a few times during the keynote.
It WAS trademarked. Apple essentially ignored the trademark and eventually reached an agreement with Cisco that included a provision for sharing the iPhone trademark in the United States.
If Apple didn't use "iPhone", I would imagine "iPod Phone" or "Apple Phone" would have been decent alternatives.