pstarr,
Much of the area which is just outside the greater Chicago area is farmland. And to the east is Lake Michigan, a decent source for fish. As the hordes move out of the city they'll pillage those next, though I would imagine they'll be a pretty significant level of violence before, during, and after. Grain, cattle, and hogs are available. Wood and pulp for fuel. Certainly there will be significant die-off, but those that rise to the top will have very likely, at least to some degree, self-organized. There's plenty of firearms and ammunition in the area, and that will become the nucleus for the new society, such as it is.
My understanding of climate chaos is that petroleum plays but one part. Coal is the largest contributor, and coal can be dug from the ground with hand tools if needed. That's how it was initially gathered, and that's how it is still gathered in some parts of the world. (Illinois has rich coal seams, btw).
But the real issue with climate chaos is the
thermal inertia of the oceans. If the linked article is correct, and it appears to me to reflect the mainstream thinking within the climate science community, we're currently feeling the effects of what we put up in the 80s, perhaps even the 70s. I can hardly wait for the 90s to arrive. We've consistently increased our CO2 and CH4 emissions over time.
So yes, I think a collapse will be beyond bleak, and no, there will be nothing fulfilling about it. If we're to avoid it, we'd have to undo many of our sins. That seems unlikely, but I'm willing to consider how it might be done. I've made my suggestions in other posts and comments.