Would Robert Kennedy have become president had he not been inated?

It can't be known. Humphrey was leading in delegates at the time, even with Kennedy having just won California. Some rumors are that Mayor Daley had already told Kennedy that he'd throw Illinois his way even though he was supposedly a Humphrey supporter. (In those days, Illinois operated under the principal of "One Person One Vote", with the one person being Mayor Daley.) The New York Primary was coming up; had Kennedy won that he'd likely have an easy road to the nomination. Had McCarthy won NY, then the nomination would be a floor fight most likely between the charismatic Kennedy and the more union establishment Humphrey with anti-war McCarthy playing kingmaker. McCarthy would have won policy points which would have altered the campaign and further split the country by generation and by view of the war. With older establishment men being the more likely to vote, the Democrats would have needed much higher voting rates from young voters and women to have won. Kennedy would have accomplished that much better than Humphrey was able to, though remember that the voting age was still 21 at the time. I believe that Kennedy would have been elected, but it is all imaginary now.