One thing most pundits agree on, and would have agreed on even six months ago, is that iPhone6 will get a larger screen. It now seems there will be two screen sizes, 4.7" and 5.5".
The step from iPhone4's 3.5" to iPhone5's 4.0" I think added a lot to the user experience. The home screen offers one full row of icons and web browsing improved greatly. At the same time iPhone remained a device you can use with one hand. That's quite important to a lot of people. I often use just one hand, but when writing I most often use both hands. A thinner design also helps keeping iPhones one-hand devices.
I've seen several smashed iPhone screens although iPhones have durable and damage resistant Corning Gorilla Glass. With sapphire crystal glass, smashed or scratched screens should be driven into no-existence. Furthermore it means your iPhone can join the keys and coins in your pocket without being scratched - well the screen at least - but the backside might still be vulnerable.
There are rumors about a protruding rear camera. I think that's unlikely, because it's not elegant enough and the device will easily wiggle on a plain surface.
iPhone6 will be presented on September 9th and probably be available to consumers on the 19th. A lot of us are looking forward to the event. I like those Apple events.