Francis Crick, one of the men who discovered the double helix, proposed directed panspermia. Not only was life on earth of cosmic ancestry, but also that it had been specifically sent to or directed towards earth.
That’ll be the fallback when complexity makes ye olde primordial soup untenable. An alien intelligence sufficiently advanced to have launched such a scheme would be indistinguishable from a god. But, I suspect we won’t be hearing the argument that “aliens did it” will halt all scientific inquiry and should therefore be rejected out of hand, for some odd reason.