The issue is that worse-case scenario is really bad. If this a) has an R0 > 9, b) can evade vaccines, and c) breaks containment, I really
can't imagine what will happen. Like I can't comprehend what will happen because it's so bad.
First of all, how would we lockdown? Completely ignoring any mental health effects, I don't see how lockdowns are sustainable, because of the economic implications and how they affect education. How the fuck are we going to produce goods and raise children without (minimal, masked) in-person interaction?
But the virus seems so transmissible, that anything below a full lockdown will almost useless. The virus could be so transmissible that even if people only go shopping and to work, and wear masks, it will still spread to everyone. Even if it's not that transmissible, I don't see how governments can institute anything near full lockdowns without something like martial law, because people are not going to want to lock down. So with an R0 > 9 it's going to spread fast.
Then if the virus is remotely dangerous, hospitals will be significantly more overwhelmed. Considering that hospitals had to triage from the last two outbreaks - I can't imagine how many people would die.
Fortunately, the worst-case scenario is still very unlikely. The virus does seem to be very transmissible. But it also seems like vaccines still prevent hospitalization and death, and the virus itself might be less deadly. The probability for any mutation to completely break resistance from a vaccine / prior infections is very, very low.
Lastly, there's still a chance we can contain and eradicate this variant. That's why scientists are holding emergency meetings, countries are rapidly instituting travel bans and infected people / regions will probably be quarantined. We have hindsight that we didn't in 2020, and we even have technology to do fast testing and contact tracing. So there's a chance that your life may not be infected by this variant at all.