I'm sure a limit will come around eventually. But plans are afoot to build city-sized data centers, and even then that's not enough to sate the AI superscalers' ambitions, hence Elon's talk about putting data centers in space. This is a level of compute scaling unheard of in our lifetime, and we're still a long, long way off from AGI. So while the juice may theoretically not be worth the squeeze at some point, with the current capacity we have there is no end within sight to the incentive to build more. It will take a number of years at least, and who knows how much environmental/economic destruction, before the dropoff in return on capex begins in earnest.