I'd be surprised if the Celts trade KO, just because I think his value to them as a shooter who can adequately defend both big positions is enough that he probably isn't worth trading unless it's a lottery pick or a two-way starter coming back the other way.
It's hard to see another team giving up that kind of value, unless there are other assets involved.
Well, I guess it depends upon what you think his ceiling is. If you think he's pretty much who he is, then I think the much cheaper JJ can provide pretty much the same amount of shooting from the big position as KO, with much more defensive versatility. JJ doesn't provide the playmaking and passing that KO does, but that's not needed nearly as much with Horford there, who is one of the best playmakers from the big position.
Further, keeping JJ next year will come at a price around Crowder's salary or a bit more; whereas, it wouldn't surprise me to see KO get more than Turner this summer.
Would you trade him straight up for Noel, or even adding a later first round pick (like Boston's 2018 pick)? Though I'm still not convinced that Philly would even want a big back in return, even with KO's offensive versatility. Perhaps if it was expanded a bit to be KO and Rozier for something like Noel and Covington, that would make more sense.
I'm not sure I'd prefer to pay Noel what he's going to get than pay KO what he's going to get.
I don't think Kelly is going to get quite as much as you suggest he could. He's a role player who most teams probably regard as a pure center who probably needs a very good perimeter defense in front of him to not be a liability defensively. He's also fairly inconsistent and has had a significant number of injuries, though no major ones.
Kelly, to me, is a significantly better player than Jonas. At times Jonas has looked really good playing with the starters, but that Jonas comes and goes. For the most part, I think Jonas is a third string caliber player who can do a good job filling in above that when necessary. Kelly is a valuable utility big who can give you solid 24 minutes a night or so and really juice your offense when he's in at center and he's confident in taking his shot.
Noel, I'd bet, will get a max offer from somebody, even though he has had a major knee injury in the past and is still very raw on offense.
My guess is that Kelly gets a deal somewhere between what Jon Leuer got (4 yrs / $42 million) and what Ryan Anderson got (4 yrs / $80 million), and I'd lean toward the Leuer deal on that spectrum.
The Celts might hold off on re-signing Kelly at first next summer while they chase after max free agents. I'm not expecting them to sign another max guy, though, and I think they'll ultimately re-sign him unless he's been traded in a larger package for a big name.