In any case though I think even if there are no huge "wow" factors with the new iPhones themselves
I think you are on to something with the "wow" factors, or lack there of...
I think Apple spoiled us in the beginning with the 2-year form factor change with the 3G, 4, and 5.
Every year there was something big to look forward to, either a new design (3G, 4, 5), or new feature (3GS=Speed, 4s=Siri, 5s=Touch ID). These were reasons for people to wait in crazy lines to get their hands on one.
Starting with the 7 basically being a spec bump and camera improvements, this cycle was broken. An argument could be made that the cycle was broken with the 6s, since the biggest featuring was the lackluster 3D Touch.
That is why I disagree with the OP saying that this is the real "S" cycle because that cycle broke a few models back.
Of course, Apple will most likely sell a huge amount of the 2019 iPhones, but the "wow" factor of the iPhones are gone, imo.