My estimation for the cost of restoring the OOT from the original negatives:
$1-4 million.
Sales for the first day of release of the 2004 boxset:
$100 million
So, let's say the OOT deluxe boxset does about half of that, just to be conservative. And lets upsize the restoration cost of the trilogy to be about $5 million. Then lets add another two million in some disc design and extras, plus all those other miscellaneous cost. Fox pays for the marketing and distribution, as far as I know. But lets highball it again and say that Lucasfilm sinks another $10 million in its own marketing and tie-ins like website features and such.
So, highballing a restored, high-def release from the negatives with a 4K or 8K D.I.: $5 for the restoration +$2 million for DVD and Blu Ray production+$10 million for marketing and tie-ins.
That's a price of about $17 million, highballing everything. But hell, let's push it up some more, just to put us further in Lucasfilm's corner and say it's gonna cost $20 million.
So, assuming the release does half of the 2004 DVD set, and also factoring in the fact that this will be one of the most popular Blu Ray releases at least in its year, let's make a conservative estimate of $300 million in combined sales in its first year of release. It ought to make half a billion by its third year in circulation. Again, being super-duper conservative. Now, part of that goes to Fox--but Lucasfilm's deal with them is extremely lucrative for Lucasfilm. Let's say they give Fox 25% of the sales.
So, for an exaggerated price of $20 million, Lucasfilm stands to right away make just shy of $250 million in the first year of release, and about half a billion in less than five years.
Yeah, poor Lucasfilm. Personally, in a more realstic setting I would cut the cost in half and double the profit margins.
The roadblock to the OOT is psychological, really, not financial. On paper it is the last gold egg from the Star Wars goose. If you were paranoid you could say that they are saving it for when they have no more product, but I think Lucas' last hurrah is the 3D releases, as by the time they are done he will be in his mid-70s and will likely be preparring to break up his empire and retire fully.