AFAIK, the ‘vault’ strategy only applies to a relatively small (and defined) collection of classic animated films. Those movies that we see coming out in ‘Diamond’ and ‘Platinum’ editions and so forth.
Their other strategy is, of course, to simply not bother transferring movies that they don’t think will sell. Black Cauldron, anyone? (On another note the complete, uncensored director’s cut of that movie still hasn’t been seen by the public).
Maybe this is where the OUT falls. But really, who knows?