Yeah, the montage rumor... I think people are just focusing on a technique Snyder used in WATCHMEN and are simply fanboying out on the idea that he could do the same in BvS to whet our appetite for JL.
I LOVE this rumor and am desperately hoping that it will be true. It
originated from Umberto Gonzalez. Of course, as usual, he does not reveal the insider source for the rumor.
I would not expect it to be
exactly like Watchmen, i.e., almost entirely in slo-mo and set to a pop song. Rather, I would expect it to be tailored stylistically to match the tone of BvS. But anyway, that Watchmen scene is utterly brilliant and artistically masterful. (Watchmen is essentially an art film that uses superheroes.)
With the Wonder Woman solo film set partly in WWI, I am really,
really hoping (see
here and
here) that the beginnings of the JSA are featured in some way (although rewritten for WWI instead of WWII) in the film. Just as the Watchmen montage featured glimpses of the 1940s Minutemen (predecessors to the Watchmen), I think it would be very cool to see the same treatment given to the JL in the end credits. Just a few glimpses. Maybe Dr. Fate and Alan Scott...
I also have my crackpot fantasy about the Wonder Woman film providing GL with a whole new origin that has Alan Scott pass his ring down to his grandson (the probability of which is virtually nil, I know). But that far-fetched aspect aside, I do want to see at least some hints of the JSA featured in WW's origin story. And that is mainly because one day I want to see a WWI time period JSA origin film in the DC Films Universe. (I think I'm going to start using the acronym of DCFU, lol!)