I'm a big Bradley fan, but I would be fine trading him if the situation dictated so.
Next season, we are going to need bigs. In order to create max cap space the C's will probably need to move on from Amir, Olynyk, Zeller and Jerebko. Ideally, we could bring Blake Griffin or Millsap in free agency, supplement that big with another in the draft like Harry Giles and bring over Zizc/Yabu to take those 4 spots.
The problem is, the big market next year is projected to be scarce. So if we can't get a max salary big in free agency, but a max level wing/guard is available it might make sense to sign that player then use Bradley and/or Crowder as a trade chip to add a top notch big.
For example say we strike out on Griffin, but Hayward wants to come here. Dealing Bradley the 2018 nets pick and some other young players for Cousins would in effect upgrade two positions at the cost of Bradley.
Even though I like Bradley, I also could see a point in the future when Smart will deserve to be in the starting role and Bradley is the most likely option to move to the bench.