I think DC has a legit chance to "get it right" here and they'll get to do it in a creative fashion too. Which is good because it won't be seen as a direct rip-off of the MCU.
The plan is simple make the DC television universe shows Arrow and The Flash part of the cinematic universe with Batman and Superman. This way the shows can be used to flesh out lesser known characters and expand the universe (which now includes key characters like Deathstroke, Deadshot, Black Canary, etc) so that they can appear in the films with fans aware of who they are. Arrow seems to fit the "realistic tone" of TDK and MOS films; and it's well liked so why not use it?
Not to mention his allows DC to play "catch up" quickly to Marvel. They'll have four franchises (Batman, Superman, The Flash, and Green Arrow) already established thus less time needs to be spent on introducing these characters in the films.
As to Batman, like I've said before, he needs to enter the World's Finest film as an established character. No backstory necessary. Why? 1) everyone knows who he is, 2) it makes him more mysterious, and finally 3) it allows the fans the option of keeping the Nolan backstory if they choose (it was popular and well known, so while they don't need to be BOUND to it but they also don't need to disregard it completely).