I thought it was pretty dumb that the I-VII saga marathons in theaters the day before TFA’s release had I-VI in 2D and VII in 3D. To me that smacks of the corporation wanting to sell the 3D version as the superior experience purely because the 3D surcharge is going to make them more moola.
But they will probably get around to doing a 3D conversion of the OT if for no other reason than the fact that it’s now bookended by a conversion of the PT and that every new movie made under Disney has been and will be released in 3D. It will surprise me big time if they don’t eventually get around to it. Remember that first trailer for the '97 SE with the x-wing flying out of the tv? It’s really not so hard to imagine them doing something similar with 3D.
The problem is that enthusiasm for the format has waned a bit in the seven years since Avatar. At this point they might as well also do Dolby Vision and Imax-with-laser versions just to fully take advantage of all the projection formats modern technology can offer. If nothing else it would give the theaters more money-making options for those saga marathons the day before each new Skywalker movie comes out.