Question. In the original timeline of Bruce Willis's character he has no interaction with the kid yet the kid still becomes the Rain maker so in the end this is what will happen again. Right?
That's one possible interpretation; that he's destined to become the Rainmaker no matter what and Young Joe's sacrifice was ultimately for nothing (though as a side effect it did presumably save Old Joe's wife unless she died some other way), or that seeing that was in fact what made him become the Rainmaker a second time.
An alternate point to consider though is that Cid and Sara's interaction with Young and Old Joe (particularly the final confrontation) also inspired Cid to finally accept Sara as his real mother. Previously he expressed a great deal of anger and resentment toward her and considered her a liar, which might have kept their relationship more distant as time went on and still prompted him to grow up to become the Rainmaker. Without Joe's sacrifice that bonding moment might never have happened.