I'm not seeing a hugely compelling reason to move on from my A13-powered iPhone 11 Pro. I've never had my battery go below 20%, even on vacation; the pictures are great already and the videos are quite solid for what they are, especially with the ability to do slo-mo which the kids LOVE with their sports and activities (jumping in the pool, scoring goals in soccer, video of them on Drop Zone rides, etc); and I can't remember ever having a hiccup with respect to the hardware. Everything I want to do is incredibly snappy on the A13.
Honestly, the lack of progress is a bit of a compliment. Their product (A13 in particular, but also the iPhone 11 Pro) is just so good that it's already at the limit of what even I could ever need from a phone, CPU/GPU wise.
Kudos to Apple because power savings will be wonderful for many, and the 15-30% speed increase of A15 over A13 might make a difference for some, but I'll be waiting another year.