I mean advanced AI aside, there are already browser extensions that you can pay for that have humans on the other end solving your Captcha. It's pretty much impossible to stop it imo

A long term solution would probably be a system similar to like public key/private key that is issued by a government or something to verify you're a real person that you must provide to sign up for a site. We obviously don't have the resources to do that 😐 and people are going to leak theirs starting day 1.

Honestly, disregarding the dystopian nature of it all, I think Sam Altman's worldcoin is a good idea at least for authentication because all you need to do is scan your iris to prove you are a person and you're in easily. People could steal your eyes tho 💀 so it's not foolproof. But in general biometric proof of personhood could be a way forward as well.