In my opinion, being a coin collector myself, I don't see how anything truly one of a kind collectible would drop in value. The old always comes back as a piece of "art." If it's one of the last of it's kind, collector's are human and will have a natural desire for being one of the few that has it or chase after it. Others would be discouraged because there's only 1 and it's unaffordable. With comics, if you have an actual signature from the artist, I do not believe that it would devalue. I mean for instance, if you had a comic from Stan Lee, do you fee1l like those comics would devalue with the movie industry and all making amazing remakes of super hero movies nonstop? Or do you think that they will replace the original spiderman with a cyborg spiderman or new improved version that the original ones will just be forgotten? Humans love history and owning a piece of history is like a silly accomplishment feeling that doesn't really go away imo (in my opinion).
I used to think that going on vacation to Rome to see the sights is the same as VR in Italy. However, when I experienced both, meh, not so much. Same with comics. I can see the comic book online and print it out in my color printer but a signed one authenticated? No, I don't think the value with devalue. Speaking of which, I do believe devalue does happen though if it's over valued in the first place (See Pokemon PSA 10 1st Edition Squirtle, after Youtube videos etc. jumped the card to $3k, it's now dwindling down to $2k as demand drops but imo it's because it was overvalued at $3k. I mean, I bought that card last year for $200 and am scratching my head on that still to this day).