This is the type of trade that I could see happening if a specific player Ainge is targeting falls to the SAC pick. For example, if he likes WCS and/or Winslow for this Celtics roster as much as I do, and if either fell to the Kings, Ainge might make a substantial offer for the pick.
The advantage of having accumulated the assets the Celtics have is that they have the flexibility to try to maneuver for specific players they like, rather than just waiting to see who is available when they pick.
The current Celtics player that makes the most sense for the Kings is Olynyk, which is too bad because I would prefer to trade Sullinger. In any event, I would offer Olynyk, the Celtics 2015 1st round pick (15/16), and the Clippers pick (25-ish) and see where that got me. If pushed, I might throw in another non-Brooklyn pick somewhere. I suspect that the Celtics value Bradley more than the Kings do (as I presume the Kings are pleased with McLemore's progression this year). Not sure if it would be enough to get it done.