The ceiling for this team is a national title contender. That's assuming everything goes well. That said, there's legitimate issues this team will have to overcome to reach their ceiling. Some of those issues are within the players control and some are not.
Team chemistry absolutely should be better this year without Vick in the mix. The counterpoint is we don't know yet how well Isaiah Moss will fit in on the court with this group yet because he's still finishing up academic stuff at Iowa. This is a question because Moss is the one newcomer who will be playing big time minutes this year and potentially be a starter for this team.
The next issue is shooting. Bill Self did a great job of bringing in players who can develop into great shooters. That's great for the future, but doesn't necessarily help with the upcoming season though. @BShark posted some stats from the scrimmages this summer and while not definitive in any way, can give some insight into progress being made. Dotson appears to have some gains, Silvio and Dave don't have three point range (I'll touch more on that later), Agbaji looks like he's still struggling from deep, McBride could earn some quality minutes with his shooting. Overall, with the three point line being scooted back, it looks like this team may be slightly better from deep than last year, but still nothing to brag about.
I mentioned Dave and Silvio's lack of shooting from outside, this is critical because it means neither really needs to be guarded closely outside of about 10'. That means opposing post defenders will be able clog driving lanes more effectively which will significantly hurt Devon, Ochai, and Garrett. Their effectiveness on offense is predicated by their abilities to drive into the paint. With those driving lanes clogged, the offense could actually take a step back this year because last year, Lawson was at least good enough from 3 that teams had to respect him out there. That doesn't appear to be the case with Silvio or McCormack at this point. I've said it before but, I'll say it again, this is a team that's going to play a lot of games in the 60's this season because of their offense.
The next area is defense. On paper, this appears to be the area where KU will make the biggest gains from last season. The combination of Doke, Silvio, and McCormack anchoring the paint is going to make life in the paint very difficult for a lot of teams. The concern with those 3 defensively is rebounding. Silvio is an above average rebounder so there shouldn't be an issues there, but Doke and Dave are not. Doke is a below average rebounder for his size and McCormack is just bad at rebounding for his size. Each are still doing a lot work on their bodies, so there is hope in that regard, but I wouldn't expect dramatic changes out of either of them though.
On the perimeter, the 4 guys who should get most of the minutes are all above average to elite defenders. Marcus Garrett is the best defender in the Big 12, end of discussion. Devon Dotson has the abilities to be an all-Big 12 defender. Moss and Agbaji are also both above average defenders. On paper, this is the best defensive team Self has had since the 2012 runner up team.
Those are all the things this team can control, the one thing they can't control and is the most concerning to me is health. Health is the one thing that can quickly derail everything this team has worked for (as we saw last season) and there legitimate reasons to worry about the health of this team.
Doke has never played a full season. We can say the wrist injuries were flukes and they sort of were, but Doke is definitely not the only person to get his hand caught in something and most people come away unscathed. Doke hasn't twice now. Doke also missed the B12 tournament in 2018 because of knee issues. Doke is a very large human being and for being as young as he is, his muscles, joints, tendons, and ligaments don't seem strong enough yet to support his frame. Doke making it through the season healthy is probably the single biggest individual factor in determining how far this Kansas team can go in the NCAA tournament.
That said, Doke isn't the only player whose health is a concern going forward. Marcus Garrett said in the middle of the Summer that he still wasn't a 100% from his high ankle sprain last year. Being brutally honest, if Garrett lost some quickness because of this and loses some of his defensive abilities, he very quickly becomes a pretty useless player to Kansas.
The other player with injury concerns is Ochai Agbaji. Are his shin issues chronic or a one time deal? If they are chronic and he loses his athleticism, he essentially falls into the same category as Garrett because Agbaji's game is based on his athleticism. Without his athleticism, he's not anything special.
Again, this ceiling of this team is national championship contender, but there are hurdles this team will have to clear to reach that ceiling and some of those hurdles are ones KU cannot control.