It occurs to me Rick's Beth dying in childhood offers an explanation for the cop-out he pulled back in Season 3 which was revealed in the Season 4 finale. He believes he's holding her back, but can't bear to lose her again. Also there probably actually are finite universes wherein Beth both exists and the original Rick has died without Beth, Jerry, and/or Summer realizing he's dead/missing. Throwing in the need to replace the Morty is a further complication.