Don't think RJ will be a star, but I think he's too talented to be Shabazz or come close to failing. He's got PnR playmaking potential which is honestly the only reason why I feel this way. Age + Production is always something that I personally value highly. He was extremely productive in a power conference at 18, that bolds well for him.
The shot will come along, it's not broken, but it probably won't be there in year 1 or 2. This, combined lack of wiggle and burst paints a tough picture for RJ. But, he's a dog, he has size, and he can pass. You hope that the NBA unlocks his playmaking ability and his reads get even better as he gets older.