Interesting idea, but something like that would be better for Jedi's 25th anniversary in 2008, in my opinion.
For the anniversaries of the individual films, I like the idea of specific figures or sets from that specific film itself, as opposed to something from the saga as a whole.
I've been thinking a little more about this, and I think now that if Celebration 4 (if it happens) is presented as less of a "30th anniversary of A New Hope" thing, and more of a "30 years of Star Wars" thing (as I assume it would be), then yeah, I'd be more open to getting an exclusive based around any of the films, and not just the first.
So yeah, that Vader Reveal moment might be good (sculpting the tear on Luke's cheek might be a stretch, though). I also like the idea of some sort of Jedi Spirits scene. They could repack the OTC Spirit Ben, and give us a new Spirit Yoda and Spirit Anakin in the same style--and maybe even include swappable heads for Anakin so that "everybody's" pleased (Hayden's head for Lucasland, Sebastian's for everybody else. . .).
Both scenes tie the two trilogies together fairly well, in my opinion.