Now, I think I know the answer to this, but I just want to make sure - can a Scheme save a Hermit from Madness?
Even though Scheme says "if" rather than "when," it's the same timing as "when" - both cards do something when Hermit is discarded from play. So you pick what order to resolve the effects. If you resolve Hermit first, Scheme will be unable to find Hermit in the trash, due to the lose track rule (which is in the Dark Ages rulebook). If you resolve Scheme first, Hermit will be unable to trash itself, but will still gain you a Madman (there's no "if you do" there).
This ruling surprised me a bit and I've been puzzling over it all day (I know, get a life, really.) Of course it will be nice to see the legendary and elusive Lose Track rule at last set down in black and blue. My impression is that so far it has mostly referred to one card losing track of another (Throne Room loses Mining Village, Watchtower loses Border Village, etc.) but apparently here a card can also lose track of itself.
One aspect I'm having trouble wrapping my head around is that the Hermit could lose itself for the purposes of trashing itself, but not for gaining a Madman. OK I guess the idea is you read both cards (Hermit and Scheme) simultaneously and decide which to carry out first, and if the Hermit is not around when it's time to execute it, you can still remember its instructions and follow the ones you can, fair enough.
Then I'm trying to think if there's any way between the Scheming and the Hermitting that the Hermit could be buried or end up anywhere other than the top of the deck, and if not why it would count as being Lost Track Of, since as I understand it for example you can still Watchtower a card from the top of your deck. But of course we don't know how many other as yet unimaginable on-discard effects that might intervene will emerge in the next week. And I guess Lose Track may just be one those arcane realms kind of like quantum mechanics where at a certain point you have to give up on trying to understand it intuitively, and just trust the math.
(Also yes I can see how it must be so annoying when people theorize about the rules without having all the facts, enough to make you wish you'd just shut up in the first place, but hey it's kind of inevitable people will muse and speculate when they're totally excited about something, that's just human nature, there it is what are you going to do.)
A final thought though: even if for lack of 'if you do' we eschew the semantic temptation to read 'trash this and gain a Madman' as one instruction - rather like "stop at the store on the way home and pick up some milk" where the consequentially is implied even if not explicit (though I suppose to a Dominion player one ought really to say "stop at the store on the way home; if you do, pick up some milk") - even granting that logical consistency, separating them and allowing a Madman to materialize
ex nihilo does at least seem to belie the expressed thematic concept, that of cards turning into other cards.