...Eventually, the only ones left will be Marco Polo and the Highlanders, and I'm sure that at that point they would find a way to make it happen. But only if interest in them is kept up.
Why they can't do 2D with a static pattern. Most animations already don't do billowing effects or other complex things. The drawn designs might look "too busy"... I'd buy both regardless.
Do I recall correctly that the Doctor first meets the Brigadier in the missing episode, and that that momentous meeting occurred off screen?
Correct. The Doctor does meet Lethbridge-Stewart for the first time. It's not all that epic iconic...
I thought it was pretty much accepted at this point that some private collector had snatched Episode 3 right out from under Philip Morris as he was in the process of getting those episodes out of Africa, and (evidently, now) has refused to part with it for any price.
After seeing the teaser again (the 3D just doesn't work), I was reading something this AM, where the episode may have been sold to a private collector (or stolen because of the belief of the alleged importance of the "Doctor meets Brigadier for the first time, oooh-aaah-oooh" scene when 60s Who just wasn't into "epic iconic moments" tropes as such)... and/or ended up getting destroyed during transit.
Another article/forum had a post suggesting a lot of episodes were destroyed out of the fear of what the BBC might do. Whatever happened still seems to be supposition all around.
Either which way, the fragility of these films is still a more significant issue and who would really acquire a reel of decaying 16mm film that they couldn't really use? (Even once, without incurring possible risk of it getting into unplayable shape as a result.) Just sitting there on its side, in visible light or in the dark, will have it rotting anyway and what are the odds the collector would store it vertically in a cool dark place? (And even then...) Regardless if it was sold or pinched or destroyed en route, by now it'd probably be irreparable so it's worthless. Hence the BBC doing the animation.
Realistically, new finds will be few and what might be found might not be properly salvageable.