Plans for a better version of the iPhone 5 are already smoking from Apple camp, following a leak of photos that supposedly showed the next iPhone's motherboard (iPhone 5S or iPhone 6, who knows?). Judging from the photos that came out, it looked like the successor closely resembled the iPhone 5, but is supposed to have better specs and a new iOS version.
According to the leak, Apple A7 is a 1.2 GHz quad core processor, compared to iPhone 5's tri-core. Moreover, it will possibly have a 2GB RAM and according to a "reliable source" (this is where you suspect this to be a rumor), it will actually have a slower RAM at 800MHz. Relax, people, it hasn't been proven yet.
New Siri capabilities are other possible improvements, other than that, we'll all have to wait and see and quit speculating for our own good. Brilliant tech enthusiasts will surely let us know.