Not iPads specifically, but digital devices. I did a show of hands poll in a big university course a couple of weeks ago, and 70-80% of students are writing their maths notes on a digital device. iPad is most popular, but Surface and other Windows devices are also popular, quite a few use Android (as do I for my lectures), and a tiny number use ReMarkable or other e-paper. Many students bring both a tablet and laptop to class, and I see handwritten notes viewed on non-handwriting laptops pretty often while they're writing other things on a tablet.

A lot of lower division math and computer science courses now presuppose iPads or other digital pen devices for working through handouts during lecture. Printed handouts are often available at request, but not the expectation / default.

On the other hand, I've seen more professors — especially in the humanities, but also upper div CS — start banning devices in lecture partially or altogether. Complete distraction (scrolling Instagram, etc.) during lecture is extremely prevalent, and they keep citing noticeable improvements in engagement after banning devices. This also coincides with a shift back to less take-home assignments and more exam-style assessment since they want greater assurance people aren't completely offloading their cognition to LLMs.

I haven't been on campus in a few years but even then paper was basically absent on campus. A class where a professor wouldn't allow tablets or laptops to take notes would be an aberration and a PITA. I remember I had to write like a paper check once and I had to physically go buy a pen since neither I nor anyone around me had a regular writing utensil on hand.

The exception was when people were taking orgo or a diagram heavy class. For that semester not everyone would have a tablet and some people would have pens and pencils. Or writing classes that still required a handwritten essay for the final exam

Not necessarily replaced. Some classes still ban all electronic devices unless you have some medical accommodation, this was in response to people not listening while being on their phones, tablets, and laptops.

Yes, iPads (at least at my university) are incredibly common. I would guess they’re at least on-par with paper. So many people swear by Goodnotes because you get all the benefits of handwriting your notes without giving up the niceties of search-ability, auto correct, etc.

I don’t know anyone who uses any other tablet besides an iPad, they’ve basically conquered the market.