I'm still on the iPhone 7 and don't foresee upgrading unless carriers offer a deal that's too good to resist (e.g. got my iPhone 7 for $649 off with iPhone 6 trade-in). I do plan on getting the $29 battery replacement around Nov/Dec.
The iPads are the only upgrades I look forward to, but even there, I can be selective although storage bumps are always a day one purchase for me.
Tried the Apple Watch but it's too thick. Until Apple can thin them down while maintaining good battery life, I won't be getting one.