I'm sure Riot has already considered the prospect of giving Rengar extra bonuses now that he no longer loses his passive stacks - like before his mediocre sized ability rework.
But anyways, it should/could be just moderate to minor buffs that Rengar gets.
Not too much but enough to make a real difference almost as much as it does to Kha'Zix.
As an added visual feature, Rengar's blade now has a small but noticeable purple tint at the sharp edges of his giant knife and wrist blades.
For reference here is the wikia page for Rengar's abilities and passives.
#Head of Kha'Zix
Hunter's Domain (3 stacks)
- 35 extra Movement Speed whilst in stealth or brush (10 Movement Speed bonus.)
Unseen Predator (6 stacks)
- Leap range increase by 135. (10 leap range bonus.)
Thrill of the Hunt (12 stacks)
- Duration increase by 10 seconds. (5 second bonus.)
Thrill of the Hunt (20 stacks)
- Movement speed is doubled and 20% Tenacity. (20% bonus Tenacity.)
