Credit where it's due. Great find. (Anything's easier than saying please, I guess.

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So when you say "beginning" you really mean "the 'en media res' that we had before." Interesting. Especially when we can swap out characters at will, as long as it is 'essentially' the same story. Swap out Hal for John, Abin for Hal and drunken pilot with out of work architect and booyah... essentially the same story. Man... where ARE we now?
Well essentially if they did a John Stewart movie (Devil's Advocate), you'd get what you got with the Superman TAS or the draft Green Lantern script by Smigel. Abin Sur crashes and X guy gets ring. In the case of the script we got it was Bluto, a "fear factor" contestant eating a Coyote. In TAS we got a Hal Jordan looking cartoon artist named Kyle Rayner. Abin Sur IS the Green Lantern introduction. However redone with Kyle, John, or Bluto it is
essentially the same story. Now I was unhappy with X-Men in terms of comic accuracy (despite being good films), but they were essentially retelling the same story with different characters. X-Men were operating indisclosed, Mutant is exposed, said mutant flees some sort of danger, said mutant shows up on doorsteps of X-Mansion. That's pretty much the start of the X-Men right there, in a nutshell with any details removed.
So how many years has to pass for the target audience of JLU to become adults? Ten years Twenty? Since we know that children don't buy movie tickets, ESPECIALLY not teenagers. Yeah right.
Children don't. Their parents do. Children may beg and plead to go see movies, but they aren't a reliable target audience. The Target audience is 20-30. Disposable income, the ability to travel in large groups, plenty of freedom to choose what they want to watch, access to most media outlets. Target audience. If you need a reminder of this look at what movies are getting made now,
Transformers, Masters of the Universe, Voltron, Speed Racer and
G.I.Joe are all in various stages of development. Why, because the former audiences of that show are now at the target age.
As for John Stewart, when will he be popular? Answer, when they make a movie about him. Being a supporting cast member in a cartoon won't make you any more popular than being a main cast member in a DTV video, or a supporting one in a Batman show. Hal Jordan still very much commands the comics, and has a stronger fan base. If you want Stewart to be more popular ultimately he must build a strong fanbase within the comics first. Superman, Batman, Wonder Woman, Spider-Man and Wolverine all gain prominence because they are iconic in and of themselves, and they gained that from their comic book status. Only Justice League Unlimited fans will truly give a crap about his role in Justice League...and by fans I don't mean casual viewers, I mean those who buy the DVDs and read the comics.
People act like John Stewart never starred in a successful critically acclaimed comic book series before... I can almost count the characters on one hand who have done both of those at the same time.
Well as Katsuro said, if you wanted to start a campfire with those critically successful comics you could warm yourself for a
few seconds. You know who else has a critically successful comic series, Captain Britain. It doesn't mean much.