I don't think it is leverage. I think it reflects Rondo's actual trade value. His season has been inconsistent, he is near the end of his contract, and he has indicated an interest in exploring free agency after the season.
IMO it's leverage. Celtics Front Office probably leaked information about talks with Dallas to gauge more interest from other teams like HOU, NY Knicks, SAC, LA. These teams know Rondo is a UFA and can sign anywhere he wants so they're using this as leverage to low ball Ainge in trade talks. Ainge wants these teams to outbid Dallas.
Players like Terrence Jones & Clint Capela from HOU, Hardaway Jr from NY, McLemore & Stauskas from SAC, Randle from LA could all be combined with 1st round picks (each of these teams 1st rd picks should be more valuable than Dallas's) and fillers to complete a trade. Ainge is using the media as leverage to get teams to up the ante in trade talks.
For example HOU calls about Rondo again. Danny can say he wants Jones, Capela, Terry, the Pelicans 2015 1st that Houston owns, and another future pick. Either HOU will give up the picks necessary or watch Rondo play for and possibly resign with Dallas (their rival)
Sacramento is another team who is probably hesitant to give up picks for Rondo (their 2015 1st rd pick is looking valuable at the moment). Sac just fired their head coach and are talking about being a winning organization. If they want Rondo, maybe these trade talks with Dallas get them to part with more assets. Also maybe Sac believes giving Rondo the choice of what coach he wants could entice him to resign and play with Cousins & Gay.
Just have a hard time believing Ainge is a big enough idiot to trade Rondo for Wright, a late 1st rounder, and fillers!!!
Don't know if I buy the whole idea of Dallas's team falling apart once Dirk leaves. Although it could happen, I feel as though Dallas will just sign a free agent or two to stay relevant and make the playoffs. A core of Rondo, Ellis, Parsons would be sure to lure a big or two to Dallas. Chandler would be 35 and could either still be capable of starting, or be the backup Center. Not to mention Dallas could make a few trades for PF's/C's or draft some with w/e picks they get to keep.