This being pushed out this week gives me hope. Digital copies of the existing Blu's are no big deal, and Disney/LFL apparently knows this. So if they were going to announce something at Celebration, it won't be a giant countdown to who cares, because it's already out.
On the other hand, if they were going to announce an OOT blu-ray at Celebration then why would they wait until barely a week earlier to put out the digital release?
"What's that? Star Wars is out on iTunes now? I think I'll "buy" it. Wait, what's this? There's a new blu-ray coming out later this year with the unaltered versions? Nevermind, I think I'll save my itunes money."
Disney would really be shooting themselves in the foot business-wise by announcing it now. I'd love to be wrong, though.
Honestly, I don't see how they can get through the convention without at least addressing the issue of the OOT's unavailability.