Okay, so say AI & MBAs are successful in replacing the labor spend of corporations on every level? What happens to "the economy"?
Why would someone want to collect promises? That seems rather silly, right? What having a lot of promises gives you is social standing. People treat you differently — better — when they give you their promises. If traditional labor goes away, the economy simply becomes you promising to hold those who have things in the highest regard; to be there as their friend when they call for you to. That is the same modern economy we already have but with less steps.
That is, if they're successful.
Who knows. I think it's better to err on the side of optimism despite the grim outlook.