Everyone is getting ready for a bull run, but who knows how long it might take. I hope you are wrong tough :P

Good question by the way. I definitely feel like vintage is also a thing online, and my only example is from World of Warcraft - a RPG, but not a card game. I don't really think there are any examples from online card games yet, since that's still pretty new, and most games forbid trading. Anyway, WoW have removed items over the years, and these tend to be worth a huge amount a few years after they are officially removed from the loot tables. But that's not directly purchasable by real money tough, so it might be a bit difference with Steem Monsters of course.