They're not going to have two versions of the same character, that's why Arrow can't use the Suicide Squad anymore, killed off Amanda Waller, etc. You already have Amell's Green Arrow, the Martian on Supergirl, Hawkman, Hawkgirl and Firestorm on LoT... Do you really need more? The Flash is the one big exception because the show got green-lighted before the movie.
If people are not happy with Supergirl's Martian Manhunter or Amell's Green Arrow, they will have to wait till those shows are over, or that WB changes its policy, till then...
On Greg Berlanti, he is very inconsistent, the last two seasons of Arrow are a mess, many think the second season of The Flash is a disappointment, and LoT and Supergirl are very, very mediocre.
And his movies' track record is even worse:
- Life As We Know It (Director): RT 28%
- Green Lantern (Writer & Producer): 26%
- Wrath of the Titans (Writer): 25%
- Pan (Producer): 26%
WB should get a good director for Booster Gold, Berlanti can help as a producer, he has some good ideas, but he's not a great writer.