Right, but the general theory behind the future release of the OOT is based on the notion that any higher-than-1080p-resolution release will require rescanning the OOT...at which point, why wouldn't you just clean it up and release it as is? Or, if they do an SE, since they'll already have a scanned OOT, why not use the cleaned up OOT as the basis for a new SE master and either re-do the effects or upscale what was done before? As you say, the cheapest route is to release the OOT in the new format, since it actually becomes more expensive to re-do the SE on top of that. And if you do release the SE, then releasing the OOT next to it (or, more likely, as part of a megaset where you have to buy all 15 discs or whatever), is pure profit, since you're already redoing the OOT to do the SE.
HOWEVER
For all of the discussion about how Lucas didn't foresee the future of high-res video, I don't think we can knock ol' George quite too hard. Jumping from 1080p to higher res requires a whole bunch of other things falling into place. Lucas may not have foreseen it, but streaming video creates a serious bottleneck for technology at the moment, or at least, that's how I see it.
You have several interests at play that make streaming a major factor. First, consumers love it. It's cheaper than buying, they don't have walls of discs they never watch, and you typically pay a low fee on a monthly basis to access tons of content. And you aren't having to upgrade your media system every few years just to play a new type of media. Second, the media companies love it. It erodes the "ownership" mentality surrounding media, because people get used to licensing it and never having a copy they can hang on to. It also helps cut back on piracy because you have nothing that resides permanently on the consumer's system (although someone will eventually figure out how to pirate stuff from Netflix, I'm sure).
The thing is, you also have interests arrayed against it. The companies that own the "pipes" over which streaming stuff flows are PISSED right now, because they just lost the FCC ruling about net neutrality. That will slow down how fast they'll be upgrading these pipes to handle more data flow. Which means that it'll slow down how fast resolutions change. You need much fatter pipes to handle consumers downloading 4K streams across the US.
I really, really doubt we'll see the 4K shift happen before 2020, and maybe even later. I mean, yeah, they're selling 4K TVs, and they're actually somewhat affordable, but nobody's making content in 4K yet, or even 2K. DVD was future-proofed for a while because it was higher resolution than the displays most people had. That meant that you could grow "into" the DVD resolution. Blu-ray came out just as everyone was finally switching over to an HDTV, so we've basically already maxed out that media. But the streaming thing is, I think, really going to slow down development of further high-res media formats. I mean, companies like Samsung and LG can make 90gajillionK displays, and put out new media formats like, I dunno, "Purple-Ray" or something, but what will slow the adoption of any of those formats.....is the people who own all the content. And they, I suspect, do not want to shift to another format. Not when they can license streaming rights to new sources, or start their own streaming services. So, in spite of the 4K displays out there, I don't think you'll see 4K content for a while.
And that means, I don't think you'll see a Disney release of the OOT for a while, even assuming the rights issues can be resolved.