What unprecedented change? No changes induced by LLMs are 'novel'. We've had much larger layoffs due to smaller technological improvements, for example. Productivity hasn't gone up nearly as much (a few percent?) as it did with electrification. What metric are you specifically thinking of?
Unprecedented change has already happened with LLMs. So this is expected.
> So far we are multiple years in with much investment and little return
...because it's expensive to build what they're building.