How/When should the new Batman be introduced? In reboot, WF, or JL?
Some feel a Batman reboot before a Justice League would be too close to the recent Nolan trilogy. So that means you introduce Batman in Justice League or a reboot after the first Justice League.
Others want to follow Marvel's formula and use a Batman reboot to build up anticipation for Justice League.
Then there's the option of introducing Batman using a World's Finest film as a reasonable compromise between the two.