A lot of macro predictions, I'll go micro where I can spot room for improvement which ultimately could affect his output.
1) Finishing with the left hand
He basically didn't have a left hand in college and he's improved a lot in that area. He can make basic plays at the rim using his left hand when he creates an easy opportunity. His crafty and creative finishes are still almost exclusively right handed. If he can get a better feel for his waitress technique with the left hand, he'll be less predictable at the basket.
2) Advanced left handed dribbling moves
Somewhat related to the first point. Right now he can explode dribbling left, in college his left handed dribbles were more escape oriented combined with body fakes. That's good improvement, but right now when he's forced left his first choice is crossing over to the right hand side of the paint or finishing with his inside hand (his right hand) on the left hand side of the court. If teams video teams stumble upon patterns how to take away those finishes going left, he'll need to spring out something fresh in order to unlock those traits again next season. Some inside out dribble, left handed eurostep or just a hesitation lock out move to draw fouls when he turns the corner and getts in front of the defense.
3) Shooting accuracy
If I look at NBA.com's shooting stats, I see Donovan just takes 2.2 3 pointers that are labeled catch and shoot, and he only makes them at a 38% clip, which doesn't reflect the quality of his shooting fundamentals. He needs to become better at making those shots and the team needs to add playmaking so he can take them in the first place. 2.2 3P FGs per game C&S? So there's 5 threes a game that are qualified as pull ups and he's only converting them at a 30% clip. If he wants to take that many of those, he needs to make more. That's more of an shooting opportunity analysis, where the staff needs to figure out how to increase shot quality or try to show better reads in situations where he's hero balling too much and could find other guys on the floor instead of letting it fly with a defender in his grill.