Both responders above make credible and valid points about conflict and theme; and to be sure, the question as posed is a little odd. As with any story, take away the conflict/s and there isn't much of anything left. At least nothing interesting. ;-)
That being said, I do believe Shakespeare uses R&J as a vehicle to present observations about the nature of conflict, and these are questions which are quite germane to the play itself. For instance, Shakespeare uses the chorus' prologue to firmly cast the feuding families in a shameful light. That they have remained engaged in a conflict that has transcended the generations so far as to lose its point and its purpose entirely, suggests something what a conflicted human race we are. I believe Shakespeare must have been purposeful in omitting any historical context to their argument - his point was that there was no point to the feuding.
Based upon the sub plots and complications throughout the play, it stands to reason that Shakespeare has a message about the fruitlessness of petty conflicts.
Based upon what becomes of Romeo's friendship with the Friar, Juliet's estranged relationship with the nurse and her entire family, and the regretful deaths of Tybalt, Mercutio, and Paris - perhaps we could say that we should be a bit more careful, particularly in our youth, about the battles we choose.
I submit this response in the spirit of trying to justify the question's intent.