> Ultimately, I think such a separation as you describe will be stable only when all natural resources are controlled by tier 1 and tier 2 gets by with either gifts or stealing form tier 1.

For that to happen tier 1 would have to buy all of the resources from tier 2. Would you sell your house and be homeless so that you can have a highly efficient humanoid robot? I don't think so. And sooner or later, what tier 2 would want from tier 1 is what they need to build their AIs, and then they'd be more similar to tier 1.