I hope Warner Brothers is Smart and decides to incorporate the mythos and stories of Arrow and the new Flash show as cannon for the movies.
I know people are saying that Warner Bros won't do that, because they won't risk a TV series telling the crucial origin stories and mythos building for their movies. But seriously, look at Arrow. Arrow already has the darker more realistic tone of the "edgy" DC movie universes. The stories told in season 1 and 2, do a great job of telling a compelling origin story that is actually surprisingly intelligently written and with fun believable characters.
It Flash is as good as Arrow, then Warner Bros could have 2 origins already told and the characters introduced and primed for the movie. They can even begin world building for the upcoming movies now.
That said, I could understand them NOT using the same actors for the movies...and I would be OK with that. Use bigger, better actors, but at least acknowledge good stories and character development are already happening in the TV space...and don't retread material you don't have to.
At the same time, I look at what DC is doing, and I wonder if they just want to tell good, interesting stories, but not have a connected world or universe. Basically treat stories as else world type movies. If so, I don't think that is a good idea.