If it didn't have the notch it would just have a larger bezel on a side, or some BS like a popup camera.
The "camera behind screen" idea barely works (for obvious reasons), and is hardly what would revolutionize mobile hardware. It's an aesthetic concern, not a functional one.
Things that might do that, larger camera sensors (e.g. 1"), week or more long batteries, total voice control, etc.
I think the point here is that the recent "big" features are all pretty minor things like 60fps screens etcetera, they are really nice but nowhere near as important as the new things we used to have every generation.
Smartphones I’ve owned:
HTC One X: 130 g
Galaxy S5: 145g
Samsung Galaxy S7 edge: 157g
iPhone XS: 177 g
I’m happy with the screen size vs the phone size on the XS, but I didn’t realize I wanted something lighter too. This phone is way too heavy. The new iPhone 11 Pro is 188g. Hopefully next time around they make something lighter.
Headphone jack, sure. But after face ID / full screen, I wouldn't go back to home button and touchID if they'd paid me...