I don't doubt the FO would go dumpster diving for bullpen reinforcements - they basically did last year - but I can't see any scenario where Nathan would pan out.
Not saying Addison Russell will end up better than Barry Larkin, but Larkin was 24 by the time he had as many career fWAR as Russell already does at 22.
Unless it's some Hall of Famer's milestone HR, it really doesn't matter, though I don't begrudge someone wanting to keep it. You can probably find someone around with a spare ball to throw back if it comes to that.