I feel like the second case with intents is the more interesting one with respect to how it could involve predicates, but this isn’t a half bad way of dealing with the issue in the contract world.
There is perhaps the issue of contracts skimming funds for using this feature if they are responsible for forwarding the funds instead of the user, the standard should constrain the implementation somewhat here, but ultimately this is always an issue with callbacks.
I highly encourage you to make a pull request on GitHub - FuelLabs/sway-standards: SRC Standards set for the Sway language , after some proper critique of the specification this could very well be standardized in my view.