Following the rule of form following function, and with Mark Price working with MKG (and as DNB mentioned, his age), I think it's too early to say he won't be a good shooter. I tend to lean towards him being a below-average shooter, but being good enough. Knocking down the open shots, and being smart enough not to take an 18 footer if he's contested.
But with that picture, shoulders and legs becoming more squared and even, and release looking to be at the pinnacle of the jump, I'd say MKG is on track to having a jumper he can rely on when he's open. He hits them in practice, and teams will give him plenty of room from 16 feet out. Those are practice shots that I think MKG is going to learn to hit sooner than later.