I think we can put the “contract” theory to bed, once and for all. John Landis said only a couple years ago that George himself told him that “Disney is going to put them out, as they were.” That’s quite an odd thing to make up / joke about, so I think it’s safe to take his word for it.

Less credible is that story from some guy on HTF (or whichever message board it was) about how Disney was going to restore the OOT in time for TFA, and then didn’t because they realized they needed more time to really get it right.

But the 2020 makes perfect sense from a business standpoint. It doesn’t make sense in terms of timing (the ST will be over by then and Ep9 will already be on blu-ray and 4k), but on the other hand that might give them a good release window to hype up and advertise the restoration.