We know, Flash and Green Lantern are irreplaceable members of Justice League, and one day DC and Worn.Bros. will have to enter this characters.
I don't think, then Flash come to ''Batman vs Superman'', because only recently DC announce then Ezra Miller will play our favorite Flash, but shooting ended, also recently. It denied that Flash appears in movie.
Now, Green Lantern. About him we don't now almost nothing. He got one solo movie "Green Lantern", not much people like this film, but I like to. Ryan Reynolds who played Green Lantern, is appropriate actor for this character (Hal Jordan). If Ryan Reynolds will play Green Lantern, it will be cool.
DC can use as Green Lantern, John Stewart, and I don't now what happens, when they do that. Who could play it?
In one day, maybe we will see Flash and Green Lantern in one film, and it will be their movie. It will be great battle!