It's a shame we've standardized on something so ancient and limited, but we'll be losing something when we give up on the standardization we've achieved. At least if we accept that basic graphing capability is crucial to high school and undergrad maths.
I'm picturing a high school math teacher trying to support 20-30 kids running 20-30 different BYOD'd devices... multiplied by 5-6 periods of teaching per day. Even if one app becomes dominant, teachers will still need to keep up with updates.
We can complain that teachers are technology-resistant at times, but have you ever spoken to a teacher? They're typically quite overworked already. Generally they take a lot of work home with them. The thought of adding anything additional to their workload should really give us pause.
I would hope some sort of de facto standardized replacement emerges. Like that free Desmos app mentioned in the article. That's not a perfect solution (students still need devices) but it certainly lowers the bar for entry. I'm sure a budget $50 (new) tablet would run it just fine. And there are plenty of older devices on the used market that can do it.
Thing is, BYOD is still really problematic. Some students will have an advantage over others. And there's the non-trivial matter of making sure that students aren't accessing cellular data during tests.
Ideally schools would purchase cheap tablets with no cellular modems and slap them into ruggedized cases. Then lend them to the kids or at least sell them to the kids at nominal cost.