Will KU be better next year? I think that question really should focus on two people, as they will likely be the key to whether the first question is a yes or no.
Will Perry Ellis be better next year? It's clear that Self wants to run the offense through Perry. That's not a bad thing because Perry is a pretty effective scorer down low against most teams. However, Perry struggles to score against size and that is a killer against quality teams with big men that can stymie him. So the key question is whether or not Perry will be able to score against bigger guys? If that's a yes, KU becomes much more dangerous next year.
The other issue with Perry is defense. I don't expect him to become a Withey or Embiid type of shot blocker, but his interior defense is pretty clearly below average. Perry simply must become a more effective two way player. His positioning and footwork must improve on the defensive end, otherwise he's your classic score 19, give up 17 player.
The second guy is Naadir Tharpe. Will he be better? Specifically on offense, will he take better care of the ball and get it to guys in their scoring zones? Naadir Tharpe was simply not effective for much of the year at making it easier for any of KU's scorers (Wiggins, Ellis, Embiid, Selden, Greene, Frankamp, etc) to get the shots they wanted to take. He got himself shots at various times, but he never made the offense easier for those around him.
Like Ellis, Tharpe simply has to improve defensively. I would go so far as to say he had the worst defensive season of any PG during the Self era at KU. He couldn't handle smaller, quicker guys. He couldn't handle bigger guys. He wasn't disruptive out front. He didn't pressure the basketball very much. The crazy thing is that I don't really see a reason why he can't be a solid defender. But honestly, if he's this poor on the defensive end next year, he probably should be pushed down the depth chart.
As for Embiid, I am banking on him being gone.
If you're Embiid, you're faced with the following four scenarios.
1) Stay at KU, have a healthy season that is 20% better than this past season. Get drafted in the top 5.
2) Stay at KU, encounter another injury and be labeled as injury prone, forcing him to either stay for his junior year or leave after two years as a non lottery pick due to injury concerns.
3) Leave now, prove his health during the draft combines (every team does a physical during that time) and get drafted in the top 5-7 this year.
4) Leave now, have them discover an issue during the physical that will linger, and drop to being a low 1st round pick.
Now, the only way staying in school works out for his benefit as a basketball player is in Scenario 1. Otherwise, he's better off going. I know most would say that Scenario 4 is worse than Scenario 2, but let's think about this for a second. In 4, he has an injury issue that is lingering. If he comes back to school, that issue isn't going to magically go away. He's just going to be playing (or sitting out rehabbing) for free. In 4, he's going to be getting paid and receiving top notch medical treatment, as whichever team that drafts him will do everything possible to make sure he is healthy.
The injury changed everything not only for KU's season, but for Embiid's future. I could have seen him returning if not for the injury. Now, I don't see any way that happens.