You say casually that it would take "only" ten million dollars. I think it could be done for much much less than that, but either way, that's a huge investment that Disney would only make expecting to make that money back, and that's very unlikely to happen.
The biggest problem is that as far as I can tell this isn't something Richard Williams would be interested in. According to Mo, Richard's position on this movie is to treat it like he died after making it .... just leave him out of it.
Would you want this film completed without Richard's supervision? I suppose pencils could be inked and made all pretty, but the whole thing would be a bit of a stretch.
They were able to finish the Donner cut without Donner's supervision and get his approval. But that's live action, which Donner had mostly already shot.
It's a lovely idea to finish the film, and I think that the people you mentioned would be more than capable of doing so - roughly the whole 1990 crew is still alive and working.
But that's not the drive of this thread for me. We wouldn't put an ad in Variety because that's not only incredibly expensive, but also confrontational.
I advise caution. We're treading in difficult waters here, and this project has gotten interest because it's grown slowly and steadily.
You have to learn to crawl before you learn to walk.
Or, to put it clearly, someone would first have to agree to release Richard's cut of the film on DVD in an unfinished state before anyone would agree to spend money finishing it.
The second option, of finishing the film, is a difficult and unlikely situation.
The first option, of just releasing it as intended, in unfinished state a la the Recobbled Cut, is not quite so crazy. That won't be happening tomorrow, but I can imagine it happening someday. Perhaps even someday soon.
Gilliam put that ad in Variety because he wanted to shame and insult the studio who had ruined his film.
I don't want to shame or insult Disney. I have a great deal of respect for the people currently running it, and so do you.
For me this project is not an insult or an attack or a call to arms. It's a statement.
"Hey, that Thief and the Cobbler movie. Someone should put that out on DVD."
Once that happens, once the general public is prepared to see and appreciate this film, and maybe Richard might even be willing to discuss it again, maybe then, in some future, the finishing could take place.