Not everything needs innovation, and trying to innovate anyway just creates a solution in search of a problem.
Just because we THINK we’ve solved the problem doesn’t mean coming at it from an entirely different angle and redefining the entire paradigm won’t pay dividends.
But this sort of innovation comes from having an actual solution that makes tangible improvements. It does not come from someone saying "this technology hasn't changed in years, we need to find some way to innovate!" That sort of thinking is how you get stuff like Hyperloop or other boondoggles that suck up a lot of investments without solving any problems.
I hadn't realised it was something so recent.
But there's obviously going to be something analogous to declining marginal utility when trying to innovate in mature problem spaces. The remaining uncaptured value in the problem space will shrink incrementally with each successive innovation that does solve more of the problem. So the rate at which new innovations propagate into the mainstream will naturally tend to slow, at least until some fundamental change suddenly comes along and modifies the constraints or attainable utility in the context, and the process starts over again.