What will the Chris Miller/Phil Lord The Flash movie be like? Nobody knows! Not even those guys. They're still trying to figure out the story of the movie, and Lord told the Hippojuice Podcast how it's going:
“We’re trying to break a story. It’s interesting, because there’s a really popular TV show out there, and we’re trying to carve out space for the movie that’s apart from that. I think we’re doing alright. …I believe [our Flash] is going to be Barry Allen. …We’re more trying to stick with the cinematic universe… iI really is its own thing and is kind of a stand-alone movie. We’re just trying to think of the best story. I think you guys will like it, it’s kind of a different take on superhero stuff. I’m optimistic!”
A different take? From anyone else I would say, 'Whatever.' But Lord and Miller? I accept that and, what's more, it raises my anticipation. When they say different, they mean it.
Other outlets are carrying the Barry Allen thing as news, but I swear to god this was confirmed a while ago. I know that I've heard that WB wants the iconic versions of the characters, not legacy versions, and so it's Barry all the way. This could be bad news for those hoping for John Stewart as Green Lantern, although I've heard zilch about that character since Danny Terrio rewrote Batman v Superman: Dawn of Justice*.
The fact that Lord/Miller are aware of the TV show, and are trying to be different from that is also heartening. But how different can two iterations on Barry Allen be? I guess the movie one can actually be Barry, since the TV one is Wally West taking Barry's name and day job. I know that season two of The Flash is going to play with the multiverse, and I know that this has been Geoff Johns' preferred solution to tie the movies and TV shows together (and it has to exist if they ever want to crossover Supergirl, a show that takes place in a world with an established Superman). If anybody is going to break the rules and bring Grant Gustin in for a cameo, it's going to be Lord and Miller.
Everybody knows I'm skeptical of DC's way of doing things, especially with the movie/TV divide. The Flash is the trickiest spot, as by the time the movie comes out the show will likely have hit many of the comics' most famous stories and characters - it's only in the hands of Lord and Miller that I trust the film not to feel like an afterthought to the TV show.
* That v is there for hashtags, right? They don't want you typing #batmanvssuperman.