The true limit is item 2 on your list. Eventually AI can take care of the food production portion of 1 and most of item 3. The fact is that energy and secure st

The true limit is item 2 on your list. Eventually AI can take care of the food production portion of 1 and most of item 3. The fact is that energy and secure storage are much less of a problem for AI and robots than people. For population replacement, you can get by with a couple thousand people. That's really only about a dozen large tribes. If the tribes are kept suitably insular and antagonistic (with either ritualized external marriage or slave-taking to ensure proper genetic circulation) that society might even be stable. The trick would be keeping the population stable.