Whilst I agree that AI costs are falling and AIs have practically infinite uptime, I fail to see how/why the current AIs will perform better overall in the work place.

The example of AIs solving mathematics is all fun and games, but it assumes that mastery of mathematics implies that everything else will also be mastered eventually. But instead we're seeing that LLMs exhibit this thing called jagged intelligence, which means that they can be extremely good in one area, but completely fail in another. In theory the LLMs could be improved if data would be available for other areas and if there are good verifiability criteria. Fact is that many fields just don't have those and would not be willing to give up their data.