The ACT knew they'd have to close some testing centers for but didn't want to be hasty or create a panic. I think they'd give the test at a single center if that's all they can do. At this point, they want students testing to keep both students and colleges in line.
It's a lot of closures, and it's clear that they sat on this for a while. I did a rough count, and it looks like they've closed about 2,500 centers. It takes time to compile a list that size, which makes me feel like they wanted this to be as close to the final list as possible.
If you're registered to take the exam, check the email associated with your ACT account. They have sent out emails to everyone, letting them know whether their center is open or not. If your center is closed, you have the option to re-register for July for free.
If your center isn't closed, plan on taking the test. They'll have been as thorough on cancellations as they can be.
If your center is closed, reschedule for July. That test has a higher likelihood of being given, and I worry some about a return to quarantine in the fall/winter.
More colleges will go test-optional, but probably not right away. Remember, test-optional is not test-blind. In most cases, test-optional should be called test-preferred. Colleges, particularly selective ones, want a score if you can give them one.