The Wall Street Journal says the next iPhone is just a few months away, but it won't be a huge update from the current iPhone 6s series. Better water resistance, bigger battery life, a thinner chassis, and omission of the audio jack could all be on the table.
http://www.notebookcheck.net/Next-Apple-iPhone-could-launch-with-32-GB-of-internal-storage-space.169145.0.html