Arguably we already have, if you concentrate on intelligence rates since 1975: the reverse Flynn affect. Those who grew up about that time no longer had to generate their own entertainment through storytelling, make their own music, calculate things mentally: everyday they had music, entertainment pumped into their homes, a way to avoid athematic, etc. And now we're evening thinking a lot less in our jobs, not even practicing the skills we learnt. Intelligence is only going to decrease.

It makes me so angry that an entire branch of "science" gets to just take data and go "I dunno man, maybe kids are just dumber". There's so much of this in social science. Take some measurable thing, and then just wildly speculate about the cause of it in an entirely untestable way, and then test that theory in ways that absolutely do not justify the conclusions. At the very least, the whole field should get a lesson in how to communicate the certainty of their theories and conclusions. You've got some guys hanging around couching their uncertainty when they're banging sub atomic particles together at the speed of light and then you've got some social science bro being like "If you move that checkbox on that form to the bottom it'll be way more effective, trust me bro I've hacked how people think".

Yeah it's as old as time to be honest.

When Plato complains about writing diminishing our faculties for memorizing things, it's sometimes treated as an example of how we've always pointlessly worried about these things, but he was absolutely correct and the transition from an oral culture to a written culture has absolutely demolished those capabilities.

Writing as a technology ended up having strong upsides that mostly made up for that (in particular our ability to communicate across distances and time, to read Plato's concerns without 100 generations of Chinese whispers), but it was a trade-off, as most technologies tend to be.