I bet it is the beginning of a rivalry, if not one that was already there and just not publicized. If I got punched by Diddy I would hold a grudge. Diddy is full of himself, stuck up and really not as great as he liked to think and I really dislike him.
People get into fights all the time and it does not start rivalries. You can punch someone and get over it, be friends. It has to do with what the punch was about and how serious it was. It could have been a misunderstanding. This does not mean they are going to hate each other.
I'm sure there are plenty of rivals within the music industry that I'm not even aware of, but quite frankly I don't care. These people are showing up and putting in work just like the rest of us. What happens in their personal lives is not really my business. Diddy doesn't even seem relevant at this day and age. I'm sure he's busy behind the scenes, but does it really matter if he punched Drake?
Diddy punches Drake and many are left wondering, what happened? In most cases fights breakout over a female but I think this goes much deeper than that. Number one, Diddy is all about money, so if I gambled, I would say Drake owed Diddy. Rivalry will always be in the Hip-Hop industry and the fight between the two will be squashed quickly- if it hasn't been already.