One of the biggest problems of this season was lack of chemistry. And that was mostly caused by not having a clear hierarchy. Multiple players thought they needed more minutes/shots than they got, which caused friction. Especially the starting line-up worked a lot better when Smart was inserted (a low volume guy) and even great when Baynes got in there as well.
From this season main rotation players as Smart, Brown, Tatum and Hayward will be back. I think it's safe to assume that this group wants more opportunities, with Brown and Tatum developing and Hayward (hopefully) returning to the offensive threat like he was in Utah.
Apart from character, Irving and Walker are very similar players. Horford is more or less replaced by Kanter, who takes more shots per minute. Then of the bench we don't have Rozier anymore, but Edwards and Langford are both shoot-first guys as well. Baynes minutes will be filled by Robert Williams and/or Theis, so that won't make much difference. Then we only have Morris left, who's minutes will go to either Grant Williams or Semi Ojeleye, so that frees up some shots.
But overall I think we'll have the same problem next year that there are too many players who thrive in a high-volume role. Brown and Tatum will be relieved that Irving is gone, but will soon learn that Walker main skill isn't supplying them good shots either. Let's assume that Hayward gets back on track, then the question becomes if there's actually room for his role to be expanded.
A lot of people assume we're going to start Walker/Brown/Tatum/Hayward/Kanter. That looks like a bad fit to me, even if we ignore the potential massive defensive problems.