You basically nailed it in your last paragraph - Olynyk deserves to play with a defensive-oriented center. Unfortunately, that also means moving Sullinger. While I really like both of them, Olynyk seems to do more within the flow of the game. Also, as you have pointed out, his entire history suggests that he should at least continue to be an above average shooter/scorer throughout his career. This doesn't mean he will reach superstar or even star status, but he has been unbelievably consistent. The fact that he is rebounding at a decent rate and is a fantastic playmaker out of the high post is just a bonus.
Sully has proven more so far and may even be a more successful player in the NBA, but both of these guys are worthy of starting, just not on the same team (the 108 ppg given up is proof of that). This team would be so awesome with a DeAndre Jordan type of center.
I agree with your post
I have said for a while I think KO is going to be at his best as a great 6th man. To give an example lets say a few more seasons Sully and KO contunie to grow as players and improve their averages.
This year
Sully 22yr old 31mpg 15pts 9rb, KO 23yr old 28mpg 14pts 6.5rb
Projected future (based on my guess)
Sully 24yr old 34mpg 18pts 10rb, KO 25yr old 32mpg 16pt 8rb
That will give the Cs two bigs with fridge all star stat lines. This also leaves 30mpg left for a 3rd big man. A player in the mold of Asik (currently 27mpg 9pts 10rb), or R Lopez (28mpg 12pt 7rb) would neatly fit in as the defensive anchor (Cauley-Stein could be a fit in the draft). This would allow the Cs to start the defensive big. Making KO the 6th man and focal point of the second O. At the end of games the Cs will have the luxury of playing two offensively dynamic bigs to close out games. The roles are different but its a similare idea to the Bulls 3 bigs of Noah, Gasol and Gibson. Three starting level bigs all getting nearly 30mpg.
I also like the same rotation idea in the back court. That could be a way to make Rondo, AB and Smart work long term.