I don't see the Celtics as having real incentive to deal, though I'm sure they are concerned with what Philly will do, with all their cap space. The Sixers must get one of these three: Lebron, George or Leonard, if they are to contend with the Celtics. They couldn't beat them in the playoffs even with Irving and Hayward absent, so they need another weapon.
The other possibility is if Lebron signs with the Cavs, and they somehow are able to sign and trade for another major player. That would also put them on par with the Celtics.
That 7th game in Boston against the Cavs was a fluke. If Boston had won that game, the media would view them differently now. I think they are a much more serious contender now than they were during last season.