I would trade Duren in a heartbeat and is the guy I would be looking to move the most. As in, if he makes it to his extension date something went seriously wrong.
Cant shoot. Cant defend the perimeter, is not a defensive anchor and plays the least important position on the floor. Zero offensive skills. Do not under any circumstances invest $25-$35M a year in a guy like that. Especially since the playoffs are the ultimate goal and a big like him is most likely to be benched in the playoffs as everyone goes small.
Nice kid, plays hard and seems to hustle. But I am not spending big money on a C in todays game unless your name is Jokic and possibly Embiid. Keep a cheap guy on the roster (under $20M) and a rookie. Invest your money in positions that matter.