Why not just have young Joe end up with Blunt and cid. You could clearly see that Old Joe's memories of his wife were fading and instead being replaced with those of Sarah's. It would make sense for Young Joe, who had never had that love, to find it in Sarah AND live to raise Cid to ensure that Cid doesn't become the Rainmaker.

In this scenario, Old Joe would still have to die, but he probably would welcome it as the last of his memories fade away. Would Young Joe only have 30 years after this point? Who knows. Who knows if Cid becomes the Rainmaker but at least Joe would have a chance to stop him without having to kill him. Without the threat of the Rainmaker, maybe Joe can outlast the 30 years, or maybe Cid could do some good with the time travel and his TK.

This type of ending just seemed more plausible than Joe just shooting himself in the chest after he "realizes" the paradox. It just seemed hokey to me.