You can check block time forwarder which allow resources to be created or consumed based on a block timestamp. There is also the shielded swaps that @apriori has been working on. I haven’t reviewed the post but based on our conversations it seems like a feasible product that allows you to swap some resources using an on-chain DEX. You reveal only the quantity/tokens spent and received but not the owners.
I do not think our description and architecture are mature enough to talk about any precise definition of limitations here. The best we can probably do is think of a thing X we want implement and try to ideate on it for a bit.