I do agree, however, with what the cartoon makers said about the team dynamic being improved in the show with John. I mean, the team dynamic is one of the things that makes me love that show and they really fit John in there well.
Like I said before, I don't know enough about Green Lantern lore or backgrounds but I think that if they reworked the character like they did with the cartoon, they could fit John into a live action Justice League movie well as they probably could with Wally (no one seems to give him love any more in this topic XD).
I'm not saying that John would stand up well in his own movie- that's not what we're arguing over in this thread. I'm saying that he could work in the team setting presented in what's looking like will be a standalone universe in a Justice League movie. They could play off of the seasoned marine attribute and maybe play into how John knows the effects of war on civilians better than any of the other League members and will take considerations based on that in battle. I'm just saying it could be fun.