Thanks for this comment, but I think this might be a bit overconfident.

constantly fighting off the mitigations that humans are using to try to detect them and shut them down.

Yes, I have no doubt that if humans implement some kind of defense, this will slow down ARA a lot. But:

• 1) It’s not even clear people are going to try to react in the first place. As I say, most AI development is positive. If you implement regulations to fight bad ARA, you are also hindering the whole ecosystem. It’s not clear to me that we are going to do something about open source. You need a big warning shot beforehand and this is not really clear to me that this happens before a catastrophic level. It's clear they're going to react to some kind of ARAs (like chaosgpt), but there might be some ARAs they won't react to at all. 
• 2) it’s not clear this defense (say for example Know Your Customer for providers) is going to be sufficiently effective to completely clean the whole mess. if the AI is able to hide successfully on laptops + cooperate with some humans, this is going to be really hard to shut it down. We have to live with this endemic virus. The only way around this is cleaning the virus with some sort of pivotal act, but I really don’t like that.

  While doing all that, in order to stay relevant, they'll need to recursively self-improve at the same rate at which leading AI labs are making progress, but with far fewer computational resources.

"at the same rate" not necessarily. If we don't solve alignment and we implement a pause on AI development in labs, the ARA AI may still continue to develop. The real crux is how much time the ARA AI needs to evolve into something scary.

Superintelligences could do all of this, and ARA of superintelligences would be pretty terrible. But for models in the broad human or slightly-superhuman ballpark, ARA seems overrated, compared with threat models that involve subverting key human institutions.

We don't learn much here. From my side, I think that superintelligence is not going to be neglected, and big labs are taking this seriously already. I’m still not clear on ARA.

Remember, while the ARA models are trying to survive, there will be millions of other (potentially misaligned) models being deployed deliberately by humans, including on very sensitive tasks (like recursive self-improvement). These seem much more concerning.

This is not the central point. The central point is:

• At some point, ARA is unshutdownable unless you try hard with a pivotal cleaning act. We may be stuck with a ChaosGPT forever, which is not existential, but pretty annoying. People are going to die.
• the ARA evolves over time. Maybe this evolution is very slow, maybe fast. Maybe it plateaus, maybe it does not plateau. I don't know
• This may take an indefinite number of years, but this can be a problem

the "natural selection favors AIs over humans" argument is a fairly weak one; you can find some comments I've made about this by searching my twitter.

I’m pretty surprised by this. I’ve tried to google and not found anything.  

Overall, I think this still deserves more research

Why not! There are many many questions that were not discussed here because I just wanted to focus on the core part of the argument. But I agree details and scenarios are important, even if I think this shouldn't change too much the basic picture depicted in the OP.

Here are some important questions that were voluntarily omitted from the QA for the sake of not including stuff that fluctuates too much in my head;

1. would we react before the point of no return?
2. Where should we place the red line? Should this red line apply to labs?
3. Is this going to be exponential? Do we care?
4. What would it look like if we used a counter-agent that was human-aligned?
5. What can we do about it now concretely? Is KYC something we should advocate for?
6. Don’t you think an AI capable of ARA would be superintelligent and take-over anyway?
7. What are the short term bad consequences of early ARA? What does the transition scenario look like.
8. Is it even possible to coordinate worldwide if we agree that we should?
9. How much human involvement will be needed in bootstrapping the first ARAs?

We plan to write more about these with @Épiphanie Gédéon  in the future, but first it's necessary to discuss the basic picture a bit more.