This wouldn't make sense because NIFs are supposed to be just straight function calls that provide immediate returns. It's a blocking interface.

If you want the behavior you're talking about you would communicate via ports, or you'd write a NIF that maintained its own off scheduler thread(s), returned immediately, but kept a reference to the calling pid, and then sent a message to that pid at some later date. Several IO related NIFs do that today.

That's actually an excellent use for Rust in this case because it can help you make that multi-threaded implementation safer and more reliable.