Don't bother with a 3D version, LucasFilm...
It's as big a waste of money as the Prequels and Special Editions were.
If you're going to do more new Star Wars, turn direction over to people who can tell good stories AND don't surround themselves with an entourage of yes-men that agree with everything you do just because you want them to. It's telling that the first two Star Wars film made had people who told Lucas what could be improved significantly and what to change to avoid being laughed out of the theater or sued. Sometimes a Gary Kurtz and Irvin Kirshner can be a good thing!
Good chance there'll be no reason for a 3D home release any way. 3D TV's aren't selling that well and a recent poll of market watchers predicted based on trends that a pullout of 3D hardware can be expected. Blu ray's here to stay but 3D not so much...
The rabid 3D-lovers do NOT represent the majority of the home video market... and the lack of quality 3D films on both cable and Blu ray tends to nip mass-adoption of home 3D in the bud, too.
TPM 3D might do okay, but I'd predict that each consecutive release afterwards will do significantly worse than the one before it. Oh, they'll make enough to pay for the 3D processes and be profitable, but it's not as if the Star Wars films HAVEN'T paid for themselves several times over already! The difference will be that the 3D grosses won't match the optimistic expectations of industry enthusiasts....
Case in point --
The only SE Edition of the OT that made significant money was Star Wars. It made enough to boost Star Wars above ET in grosses and just behind Titanic. (Gone With The Wind really is the highest grossing motion picture history if we go back ticket sales and home video sales...) People got more annoyed with the SE changes over time and there were huge drop-offs for the theatrical SE's of both Empire and Jedi.