You mean it might not be around September 20 like the last 5 generations? (5: 2012-09-21, 5s: 2013-09-20, 6: 2014-09-19, 6s: 2015-09-25, 7: 2016-09-16)
The iPhone 4 was 3 weeks later on 2011-10-14. Only the SE was released not released in Fall, on 2016-03-31
Apple sells a few hundred million iPhones each year. Just let that sink in for a while.
Unless someone invents a brand new way of constructing OLED panels or a time machine, the 7S/7S+ won't have it.
There are rumors of an iPhone Pro that would have edge-to-edge OLED and IR face unlock and world peace built in. It would also be priced so ridiculously high that Apple could keep up with the display production.