I think a new release of the OOT will see the light of day simply because new Ultra HDTVs with a resolution close to 4K are starting be sold (heavy prices for now, of course) and my guess is that Disney will want to release the OT in Ultra HD at some point and since (from what I know) the special editions effects were only made in HD, then the only way to release the original trilogy in Ultra HD, without some scenes to look softer than others, is to make a (at least) 4K scan of the untouched original movies and release it without the "new" effects...

That said, Disney could first release the new sequel trilogy in Ultra HD then, later the original trilogy, so it's not for tomorrow morning, if it happens.

The funny thing is that since the prequels were shot in HD, they could not pretend to have a Ultra HD release (not even one of those "mastered in 4K" blurays...), unlike the OOT!

EDIT: so... if my thinking make sens, I think originaltrilogy.com should start a petition for the original trilogy to be released in Ultra HD 4K (when the support will be defined. I guess it'll be some kind of "Ultra Blurays"), because there's only one way to release this, and it's the OOT.