Yeah. I’m guessing technologies would start to get lost if we went below a million without careful planning, but even then we have centuries of exponential decrease to go before we’re really in trouble.
Even without automation, less people means less consumers, so the only pain is short term as there’s a ton of decrepit old people (like me if I’m still around) for the youth to care for. Some large projects might lose economy of scale, but then again anything finite like land will get way cheaper.