I'll wait and see what Williamson is cooking before passing judgement even though DC's track record doesn't inspire much confidence.
I would say the JL isn't good for any member of the Trinity (though more so with Diana than any Superman and Batman):
-Superman: Frequently turned into a jobber so other characters can contribute. Or treated like a naive sap and is only nominally leader and never in action.
-Batman: turned into a paranoid nut job in order to make him fit the League when in his solo comics he is supposed to be just a noir themed detective in a bat suit.
-Wonder Woman: treated like a female Superman, jobber, Superman's baby mama, very little of her mythology makes it in (frequently in unflattering ways), written like a succubus for evil Superman or a fangirl for Batman.
Having read a lot of JL comics from the 70's all the way up to the end of the Detroit era plus being a fan of the JLA: Year One, I think Flash and GL should be the 'heart' of the JL team and should be at the center of running the team, not the Trinity, who should be off in their own corners of the DCU or running their own teams: Batman with the Outsiders, Superman with the Legion or the Superman Squad and Wonder Woman with the Holiday Girls and Justice League Dark.