Well, if we're being completely honest with ourselves, this whole hobby is worthless. All the figures. All the comics. All the action flicks. Utterly worthless. Our attachment to them is out of nostalgia that was formed in the first two decades or so of our lives. You take that, and then you throw 200$ per pop on them. And that's just the figures. I'm ignoring prop replicas, Lego sets, action figures, Omnibuses, single issues, Absolute Editions, whatever collectible exists in our bubble. It's all absolutely meaningless. You could chuck them out of your home and nothing would change. You could go back in time and prevent yourself from ever getting into such nerdy things, and I honestly think your life would be better. The simple truth is that we're still discussing these things based not on objective quality, but our childish connection with them. Any way you cut it, that's what it comes down to. The Avengers, the JLA, Terminator, DMC, whatever it may be, it's pop products designed to be consumed and thrown away; they're the fast food of entertainment. And if you were a very career oriented person, you could expand that most novels, movies and whatnot. The majority will be forgotten in the coming years. You already have classics being left in the dust, and cinema has been a thing for a century or so. It's their nature. Only a few things pass the "Great Filter".
All that said, this type of collecting anyhow, isn't about value. It's about buying stuff that represent those things that left a mark on you. That's why I'm against the "gotta get that to complete that because it is tangiably related to this" type of collecting. I think you should sit down, find the stuff that you still have an attachment to, and then pick from those the ones that still matter in one way or another. You'll end up with a franchise or two, a couple of characters, a few runs and movies. And that's enough, really. Otherwise you remain stuck to the past, desperately trying to capture a past nostalgia that might not even exist, ending up with a cluttered rom filled with utterly meaningless things; action figures, plastic statues and replicas, all representing robots, musclemen and monsters. But if you choose, you create a small collection that represents, for better or worse, a part of your life, even if it's about Space Mauhreens or Elves or whatever.
What I'm getting at, is that if you're concentrated on just a couple of Pop Culture[SUP]TM[/SUP] things, a new version coming along won't bother you that much. Because you'll like the character enough to get it. Or you'll be satisfied with the one you've got. Or you'll throw the cash because it's a one-time expense, instead of trying to juggle the POs for a dozen different things. An example. You like Darth Vader. You've got multiple Anakins and Vaders, in various formats. Satues, figures of all scales, whatever. A new version comes along, and if it's so much better, you pick it up. You don't have to worry about the new Han/Luke/Spider-Man/Kirk/Cap/T-800/Hot New Property Fad #2658. Your thing might be Star Wars or a hodgepodge of stuff or anything else. The point is buying only the things that bring you some sort of joy, instead of treating the whole thing as some hoarding completionist's nightmare. Because that way it'll never be over. These things are designed in a way that it'll never be enough. New costumes, new movies, reboots, whatever. And if you go in with a speculator's mindset, then you never really liked those things to begin with; you were chasing a profit. And there are much better ways to make a profit than buying 300$ figures and hoping they reach 1K on the aftermarket. I like it when a piece I own ends up costing more than I bought it for, sure. But I'll never sell it; it's just an ego trip to see something you have be worth more than you paid.
Bottom line is, if you're worried about importance and longevity, get into collecting real art, assuming you've got the money. These things are just fun distractions that we like to look at. None of it is important. None of it will be remembered. All of it will most likely have a superior version coming out at some point. But if you focus on only the few stuff you legitimately like, then that won't bother you because you'll always get some enjoyment out of everything.