I think the '97 version should be included alongside the OOT. It's got a certain historical value to it, and the SE of ANH is still the highest grossing January domestic release in history if I'm not mistaken.
But people would probably scream bloody murder at having to buy not one, but two of the revised versions just so they can get the original. That's what makes me think Disney will simply include the original version and the "most recent" version and call it a day.
If they really wanted to justify the '97 version's inclusion in an ultimate blu-ray set they could just go fucking nuts with any additional changes they want to make for the "final" SE. That way there would be less redundancies and future viewers could chart the evolution of these films throughout their three theatrically released versions (77-83, '97 and 2015).
I'd be fine with the 2004 and 2011 versions being "forgotten" in future bd sets, especially since the latter already had an official blu-ray release and the former is nicely preserved from the hd broadcasts. The most recent work done by teamblu to preserve the '97 version is exemplary, but it could still use some love from the official source.