Am old enough to remember the Kennedy Presidency, and Robert Kennedy as Attorney General. Worked briefly in his campaign, stuffing envelops, one afternoon.
Could he have gotten the nomination? Johnson was an acknowledged foe, Humphrey had more delegates, still there were a number that were not for either of those two. Remember hearing his speech in Indianapolis, for an off the cuff speech, few have surpassed it for the event. Indianapolis, was the only large city in America that did not break out in rioting that night, thanks to RFK.
Would he have beat Nixon, we will never know, alas.