Bloomberg is reporting that Apple is developing new iPhones that feature curved glass and larger screens:

"Two models planned for release in the second half of next year would feature larger displays with glass that curves downward at the edges, said the person, declining to be identified because the details aren’t public. Sensors that can distinguish heavy or light touches on the screen may be incorporated into subsequent models, the person said."

I think it's almost certain that Apple would be working on different sized models and I look forward to what the iPhone 6 will look like!