The Magic might make a move before this trade deadline to help Dwight or they might do nothing and hope to make a move at the end of the season. The most likely outcome of this situation is that the Magic keep Dwight Howard through the end of this year, hoping to resign him. However, the most likely outcome of Dwight hitting free agency would be his departure from Orlando.
Dallas has been using this season to dump salary and do what ever it takes so when the free agency period comes this summer, they will be able to pair both Dwight Howard and Deron Williams with Dirk Nowitzki to form their own Big Three. Deron Williams is probably already looking for homes in the Dallas area and will be signing there, at first opportunity as long as the Nets do not acquire Dwight Howard. Mark Cuban wants both Deron and Dwight, and he has a good chance of doing so as long as neither is traded this season.
The Nets would still be contenders for Dwight in the free agency market. This is actually the preferred way for them to acquire them as it would allow them to keep a high draft pick for their awful play this season, as well as keeping MarShon Brooks and maybe being able to trade Brook Lopez for another quality player. Should the Nets be able to sign Dwight Howard, retain Deron Williams, keep MarShon Brooks and trade Brook Lopez for a quality Small Forward, they would have a formidable lineup for their move to Brooklyn.
Boston would be another contender to sign Howard. They will be finished with the contracts of Kevin Garnett, Ray Allen and Jermaine O'Neal at the end of this season, which should give them enough cap space to sign Dwight. They would be able to roll out a starting line up of Rajon Rondo, Paul Pierce, Dwight Howard and attempt to either re-sign Garnett and Allen to lower contracts or start Brandon Bass and sign another free agent shooting guard.
The last team that would be able to sign Dwight Howard, if he hits the free agent market, would be the Los Angeles Lakers. Dwight has said he would not sign an extension with the Lakers if he is traded there, so the chances of him signing outright appear to be slim. However, if your Kobe Bryant, the possibility of having both Dwight Howard and Andrew Bynum on your team has to be tempting. The Lakers would then be able to turn around and trade Gasol for a quality point guard or small forward. Boston (Rondo, Pierce), Houston (Martin, Scola) are just a few teams that would be surely interested in the All-Star Power Forward. Those roster moves would make the Lakers a team that would rival even the Miami Heat.