I don't think I'll miss anything serious from skipping upgrade cycles. I'm not much of a camera user and Face ID is meh to me so From iPhone 6 to XS I've barely seen any improvements I care about other than water resistance which was a 6 -> 7 upgrade.
If I could find a suitable replacement for the Apple Watch (which I find very useful) then I'd be very tempted by this.
I've got the latest watch and it is very good, so although the price is high it does not seem particularly unreasonable.
iPhones, on the other hand, give me the impression of being very expensive for what they offer and I find them unsatisfactory in a variety of ways. Currently, I plan to keep the iPhone 8 for as long as I can then decide what to do depending on the state of the market; this will probably involve getting a reasonably-priced Android phone with a custom ROM and some sort of fitness tracker.