I haven't seen enough of Kris to have an opinion, but based upon what Fran and Kenyon have had to say, I'm excited.
Obviously Keegan has NBA potential. I'm not sure when he'll get there, but in my opinion here is what he needs to improve upon to realize that potential:
His length, athleticism, and effort already make him a very good defender and rebounder. He reminds me of a Dennis Rodman starter set in that regard. That said, he must get better at keeping players in front of him on the perimeter, which will occur with experience, as well as progression of technique and foot quickness.
He already looks like a more natural outside shooter than his father (sorry Kenyon), and his shooting technique is really solid. His mechanics look very consistent and repeatable. This will continue to improve as his role on the team evolves. With the departure of a couple of shooters, that should already begin to occur next year. If he can shoot from distance and get to the rim (which is already a strength of his), he will have a role in the NBA, and I would predict that ne is most likely to be as a starter at that level, not a role player.
The NBA is full of freak athletes. He has shown that he can compete at the rim both offensively and defensively at the college level, but he'll have to expand his moves around the hoop to compete at the next level. Again, his athleticism and length mean that he can accomplish this. If he tightens his handles a little bit, I can see him excelling with the Euro step and other slick moves that get him to the hoop, and his arm length combined with a soft touch will allow him to get to the rim and finish.
It's likely that he'll need another 10-15 pounds to bang in the league. That shouldn't be a problem for him, and he looks like the type that will maintain his athleticism as that occurs.
I am excited to see him develop, and what we know about Keegan should give us much optimism about Kris as well.