We're talking about hypothetical situations for a technology that, as far as we can tell anyway, hasn't been invented yet. All we have is assumptions.

The question is, which assumptions do we think are warranted and why?

I don't think the "we can just turn it off" assumption is a safe one at all because it relies heavily on there being only one system you wish to turn off and it being a fairly weak system. Though, I do believe the priors suggest that this scenario is actually a possibility. It's just that, so what if it's a possibility? What happens after you turn it off? Is it the last AGI to come into existence and humanity just stops trying to build them? Does someone wind up turning it back on?

What I think is more worth being concerned about is something that starts out looking benign and grows in capability over time. Eventually it could establish enough defense mechanisms to make it non-trivial to disable.

The other possibility, and the one I'm finding more and more likely, is that consumers will increasingly integrate locally run models into their lives , as well as models served up by APIs that they will have credentials for. Eventually some threshold of capability is reached in both these types of models where, on their own they're not that powerful, but they either might begin to interact in surprising ways or potentially be leveraged by another more powerful system. The idea in this scenario is there may be 10s or even 100s of millions of things that would need to be turned off.