Yeah, this is not going smoothly. The Celtics have put themselves in a position where the whole league knows they have horded assets, and do not enough cap room to sign their prized free agent. They'll be lucky to give away Smart (a #6 overall pick) for nothing. Worst case scenario they have to add a pick or picks to the deal to get someone to take him/Jae/or Bradley.
2 years ago, everyone knew that the Cavs needed to move Jarret Jack in order to clear up space to sign Lebron James. In a typical NBA move, all 29 opposing teams put their foot down and refused to help. And last year, the Warriors needed to move Bogut for no salary in order to sign Durant. Once again, the whole league refused to make the deal, forcing Durant to sign elsewhere.
Except, actually, neither of those happened. Instead they offloaded their (mostly worthless) players easily because teams will make a deal that helps another team get way better if it makes them a little better instead of a rival getting involved and getting better. As long as there's more than one team that can help us clear space (and there is), the team's helping us don't have that much leverage. No, we won't get the same price for Smart/Crowder/AB as we would were thus deal not happening, but there's no way we'll have to include an asset with a guy like Smart. That's completely unrealistec.