what are you talking about? are you referring to the whole "i cant one shot a target with my first ultimate" kind of deal?
well no shit man, when you see clips of rengar blowing someone up instantly he is fed in those clips. When rengar gets his power spike and items he can already one shot someone, it just takes him gold to get to that point. this is why a fed rengar takes over the game. he just picks someone off, farms, picks another person off. and then comes back even strong. then can just pick someone off and blow up his near by teammates trying to come help him. rengar is quite strong right now in solo queue.
I think rengar needs no buffs whatsoever, if anything the cat needs somewhat of a rework to encourage a bit more counterplay. that is hard to do though because the most fun part of playing rengar is the ult explosion on a squishy. so if you gut that the players who love him now are going to be pretty upset, granted I don't think that should stop a rework, but still it something I'm sure riot considers. Rengar does not need buffs though, regardless of what happens.