I just got done reading Flashpoint as i waited to get the whole series in one. I think that the translation of this story to film will make for a very entertaining event. A great lead up to Justice League Movie which will make sense as a stand alone , tied to no other movies franchise and also a great way to do a Flash movie where his Powers and Character play more of a relevant role as he is the one who has to save the universe from destroying it self.
We as Fans need a great Flash movie and a Justice League movie. WB does not want to bridge together their movies to a lead up and want to make a stand alone Justice League movie that has no ties to previous films with their own cast.. I think This will be the way to go to kill two birds with one stone.. Watchmen style. It could start with a Montage that shows the Justice League in Action.. Then lead up to the Office scene where Barry wakes up Right after the opening credits to discover everything is different.. The story can go from there.
This will also open the doors to try out a lot of tier 2 DC characters that got to shine in this movie.. and also a way to give people the the batman who has gone to the darkside, a bitter, grieving Thomas who has no issues with killing people. I think a look at that Batman, with an oldie like Eastwood or the guy that played the Comedian (i forget his name) losing some weight playing him will be interesting. But for me i guess the real deal is that we get to have Flash as a headliner in a movie that gives him a conflict which really has the viewer rooting for the guy to win. Also , Superman, seen in the state that he is in the Flashpoint universe kinda makes the threat all the more real. It was a very different take than the generic "superman is evil" route they usually take with elseworlds stories.
With this, the Movie could end with that last shot from the comic showing the new league.. and with this said, It will only be natural if it evolves into a JL movie that adapts the Darkseid storyline from the new 52..
This is just my opinion on this matter though.. so feel free to let me know what you think at the usual place. and thanks for reading!