I think, from what'd you've listed, Aaron's Thor is the biggest chance. Maybe early Ms. Marvel? Or Moon Girl and Devil Dinosaur (something scholastic sells alot of)

Stuff like Hellboy and Usagi, while great, I don't think will even be a classic, evergreen story like DKR, Watchmen, etc. I'm sure there's great stuff from the 60s and 70s that we don't talk about from smaller publishers. Hellboy probably has a better chance, since it has better trade availability and the movies.

I think Walking Dead will sell for a long time, because of the show.

I don't think time will be kind to Saga, but we'll see how it goes if and when it continues.

I can't see any of the event being 'classic'.. I mean, even stuff like Crisis or Secret Wars are only 'classic' in impact, they're not really things people seek out and read.

I don't think any Marvel event had that sort of impact.. maybe Civil War, but that was more an impact in style than in-universe stuff.

DC keeps changing the universe, so it's not like you need to read old stuff... I can't see much there, either.

Astro City maybe? That'll read alot better in a set of trades than when the issues dribble out.

The stuff that Paste Pot Paul mentioned that becomes classic evergreen sellers is stuff that has reached and resonated with an audience beyond the hardcore comic fan audience-Dark Knight Returns, Watchmen, Sandman, Preacher, et. al all reached a wider audience without adaptations in other media vaulting them into the public consciousness as something more than just favorites with fanboys. They are all more or less self contained as well and tell complete stories. It may take 10 volumes for Sandman to do it while Watchmen and DKR do it in one, but those 10 volumes are self-contained and offer up a complete story when all is said and done. They offer resolution and pay off that provides for a satisfying and memorable experience for the readers who invest in it.

I don't see much from Marvel and DC doing that these days as not much of their output these days is geared to an audience beyond the Wednesday warriors or accessible to such an audience the way Watchmen, Dark Knight, etc. were. They aren't hitting the notes of self-contained complete stories that offer resolution and pay off for the audience.

I think modern classics will come from other areas of the industry...

from Image I think Saga (especially since it got street cred with its Hugo awards) and Walking Dead have a chance to get there (assuming Saga finishes up and tells the complete story) since they are on target to hit the kind of notes needed to emerge as a classic evergreen seller, it's a question of will it get there and how will the endings play when all is said and done-Walking Dead has ended but I haven't paid attention as to how the ending was received, Saga hasn't reached its conclusion yet, so it's too soon to make a call, though it is on the right track.

Hellboy and Usagi miss on a couple of the notes. Hellboy is not quite self-contained, there are too many spin-offs and stories outside the main Hellboy arc that impact the Hellboy story itself, and Usagi isn't yet a complete story though many of the arcs are, but it hasn't really reached that wider mass audience for it to vault into that arena. Things like TMNT have the reach but not the complete self-contained story.

I have a suspicion that most of the next generation of classics will not be stuff that had much of an impact on the direct market. They will be stuff that came from either smaller publishers in the direct market that reached a wider audience outside the direct market, or stuff from major book publishers with graphic novel imprints that do not focus on the direct market and don't release as periodicals first.

There are a few that I think are already on the verge of becoming such modern classics the best example of which is...

Bone by Jeff Smith-self-contained complete story, with resolution and emotional payoff for readers that reached a wide audience outside of the comic hardcore base because of Scholastic sales. For many, it is already there, and the upcoming Netflix animated series will likely cement it's place in that echelon of evergreen selling classics. I'm not sure Bone will go out of print any time in the foreseeable future.

The picture is a little more cloudy on the others.

The dilemma as I see it is that most of what has emerged as classics i.e. evergreen sellers that have transcended the confines of just a comic fan audience were projects that were NOT part of the shared universe or produced in a sandbox with diverse hands shaping it. Most were special self-contained projects with an intentional limited run (Dark Knight, Watchmen and to an extent Batman: Year One which was a "mini-series within a series" rather than a standard release as part of an ongoing series) or longer series that would up having definitive ends (Sandman, Preacher, etc.), and all were the product of single unified creative vision guiding the entire product and giving it a unified voice and visual look. The overwhelming majority of content put out by Marvel and DC currently does not meet any of those criteria so I don't see much of that stuff achieving evergreen selling classic status.

Runs that do check all the boxes include things like Bendis' Ultimate Spider-Man, but it seems to have lost steam and popularity over the last 5-7 years, but it seemed on track to make it for a short time. So even if something checks all the boxes, there are intangibles at play that make things hard to predict. But I would guess that a handful of the Raina Telgemeier OGN's will be in the class of modern evergreen selling classics, joining Bone, and maybe Saga and Walking Dead. Beyond that I don't see much checking the boxes and having the kinds of intangibles to make it. I do think more of the future classics will be stuff that was targeted to the young adult market rather than the adult market as things like Watchman, Sandman et. al were though.

-M

Note:  I think there have been far, far, more really great long-form comics produced in English in the last 20 years than in all of the 20th century.  

New Classics?  Fun Home. Persepolis. Quality of the work matters, but outside media attention matters more. As far as recent books that are getting a lot of critical acclaim, I'm really hoping My Favorite Thing Is Monsters sticks around. (But they don't always! Exit Wounds kept getting Best of the Year accolades, but I never hear it mentioned today.)

Edit:  Probably March, because it'll be the graphic novel that is taught in black history college classes.  

I get your point about self contained stories, but it doesn't mean arcs like Hush don't strike a chord, whether for the value of the story or the work of a writer or artist of note.
Even saying that it's hard to see specific stories standing out from the crowd these days.
Walking Dead may be a phenom for some time, I certainly hope so.
Usagi's done in one (in general...I get that it has an overall saga to it) would probably work against it even if it were more popular.
New Frontier would be another modern classic for mine, though it's a bit older than what I've tried to touch on. Though to be fair most of my suggestions are older too.

I would argue Hush is like Batman Year One, a mini-series within a series that is not necessarily part of what came before and after it in the ongoing series, so passes the test as a complete standalone story.

-M

I would think Hellboy will have some serious staying power, not only do the trades get continued re-releases with trade dress that makes them easy to follow but they even recently got new omnibus editions that look even better and collect more of the story per book.