The way i see it the after the  disaster that was Green Lantern the Flash movie, which seemed to be next  in line, won't be happening any time soon. After all, the Flash project  that is in  production right now has the same people behind it that did GL.  Berlanti, Green and Guggenheim are writing it and Geoff Johns, who  seemingly played a big role in the GL production, is also heavily  involved. 
And besides, just like with Wonder Woman, they've been unscuesesfully  trying to get the movie off the ground for a very long time. There have  been 5 screenwriter (teams) on the project in 6 years, which kinda  proves that nobody seems to be able to come up with something the studio  likes enough to actually greenlight it. Back in 2004 they had Goyer,  who's approach seemed like the most promising to me. Then they gave it  to Shawn Levy, before replacing him with David Dobkin and Craig Wright,  who were hired to write the movie as a JL:M spin off. After that went  nowhere, Dan Mazeau was supposed to write a script based on a treatment  by Geoff Johns. Much like with Johns' Captain Marvel movie, we never  heard anything about it again until they announced the Green Lantern  Writing team was now also doing The Flash. 
   
   So after GL failed the way it did i doubt they've gained confidence in  characters they obviously didn't have enough confidence to greenlight a  movie before.
  
As i've said before, from my point of view, the best thing to do next for DC Entertainemnt would be to go with the JLA  flick and continue form there. Since it features their two big  guns, Superman and Batman, it's a much saver bet than anything else they  can do right now. And it could also built some new momentum for the  other character that could lead into some solo franchises spinning out  of it. 
Personally, i never got that single minded way of thinking some fanboys  seem to have. These movies don't need to get bigger and bigger  with the biggest one of them (the team up flick) coming last. The way a  studio looks at it, there is no endpoint to these plans anyway. Just  look at what Marvel is planning after Avengers. They won't continue with  flicks like Secret Wars or anything like that, they will do Iron Man 3,  which seemingly will be on a much smaller scale storywise than what  came before. 
 
 And as for the need to introduce these characters in individual movies  before the team up flick... i think that's very overrated and leads to  exactly what we're seeing right now... pretty much every movie following  the same boring (origin) formula. There are so much things you can do  with these comic book proporties that would translate into much more  interesting movies that really don't need the audiance to know every  detail of the origin story of every character the movies features.