Yeah, they'll find dodgier sites composed of even more illicit material hosted in places Texas can't reach. It's not like it's hard to find other sites by going to google and searching "porn".
Basically this, it's been years now since Pornhub purged anonymous content (and by extension, pirated material), so anything that targets it is redundant.
Yeah the irony of the focus on PornHub is that 1) they were never any worse than the other dozen major sites which still accept anonymous uploads, and 2) they're now one of the most squeaky-clean porn sites out there.
I mean, as clean as you can be when you allow users to upload porn, but by forcing out those who adhere to the rules you instead empower those who don't.
They'll just go to to one of the million other sites that don't enforce this at all. Which may actually be worse, since many of those sites are far less scrupulous about sharing data and spreading malware.
You assume that kids today know as much about technology than when you were their age. I can assure you - it's not the case. They might know what is VPN and how it works, but they do know how it install it from app store and avoid geo-restrictions.
I'm guessing that (just like actually happened when I was their age) one kid will figure it out (or read about it, or have an enabling parent tell them how to do it under the presumption of good reasons) and then tell all their friends how to do it.
Even if they don't know now, put an obstacle in their way and they quickly find a workaround. Hell, as a kid the we learned how to bypass bios password within a day, because me and my siblings very motivated indeed. The trick was to not let parents know that we knew. That part lasted a week. We got greedy.
I'm sure they already know. I see people that I've least expected are using VPN providers all the time. It's a lot easier today than it was when I was a teenager.
In my teenage days, VPN was only used for: corporate site-to-site, illegal activities. It all required a manual fragile setup. Today: download an app, launch that app.