Apple is a creature of habit; they'll more than likely release the iPhone 5S or 6 soon. It's still only rumoured at this point but since iOS7 was just announced, I'm sure a new device will follow shortly.
It's expected that there will be an iPhone 5S. It will probably include an even faster processor, maybe 2 gigs of ram and a 13 megapixel camera so it's equal with android phones. Also it looks highly likely that there will be a new, low end, iPhone for developing nations and prepaid carriers.