Even though the movie and TV universes are separate, Warner Bros. may run into the problem of having two actors play The Flash as the Grant Gustin version is extremely well-liked and popular amongst the fans (something Marvel won't have a problem with).
Now while on the set of his latest movie, the Harry Potter spinoff, Fantastic Beasts and Where To Find Them, Ezra Miller talks about his version of The Flash with EW.com:
"Well, [first] it’s going to be a movie, I’d like for it to be an exploration of a human being, a multi-dimensional human being, to speak…Wow, I just made such a pun, without meaning to…. I’d like the character to have many dimensions. But really, I’d like him to have the usual dimensions we know and love, and then some extra ones that are part of the amazing consideration of this superhero. I hope to realize him as a person, and I think what’s most exciting for me in superhero mythologies is when we feel the humanity of someone who is heroic — or the heroism of someone who is a flawed, deeply human person.”
Last week also saw Batman producer Charles Roven weigh in on the popularity of The Flash, with Roven confirming there are separate universes. Interestingly enough, Roven states he doesn't have the answer regarding the popularity of The Flash TV series affecting the movie. Check it out below.