Apple knew it back in 2017 and as each year progresses it’s becoming increasingly clear we have exited the innovation phase and are well into the saturated/sustained phone market. We will never see an iPhone announcement quite like the first 5 and the X. Short of a form factor change, our phones will last longer and the new phone feature list will decrease year over year.

Also - the Pros are thicker, heavier, and slightly taller and wider than the X and XS. Couple months ago someone linked to an article on how much bigger iPhones are getting and this year continued that trend.