Lucasfilm has been running itself for a while now. They have a lot of material to work with. That's why they have been withholding a lot of content regarding video releases. According to a friend who knows insiders at Lucasfilm, the projection right now is a 50-year plan, that is, stretch out the material to keep the company alive for fifty years into the future. Supposedly, every single piece of film material--every take, every foot of film--from the star wars movies has been scanned in 4K and is sitting in computers. Few have seen it all because it comprises hours of footage.

And yeah, I'm willing to bet the OOT is included in that. I'm sure they're sitting on it for long-term investment reasons. Maybe the 50th anniversary, once Lucas is out of the way?