This is my feeling too, but I've nothing substantial to back it up. Can anyone here shed some light on the legal aspect?
Shouldn't be a problem. WBIE is the publisher.
And all the movies have been from WB. So, unless there's some insane fineprint somewhere, everything from Batman 89, Batman Returns, Batman Forever, Batman and Robin, Batman Begins, The Dark Knight, and The Dark Knight Rises should be fine.
The only one I believe there would be issues with rights, and not usable, is from the 1960's Adam West Batman show and movie. That was done in conjunction with FOX, which last I checked is the reason there's no 1960s TV series boxset.
Pretty sure if they wanted to do a movie costume pack of skins, they'd be able to do so. Which, I think would be great. They really do great work with actually doing different models of Batman in AC. DKR Batman looks like a completely different person, as does Year One, and the Neal Adams 70's model even looked thinner, with there being different jaws for some as well.
So, if they'd do a movie pack...I'm sure they'd nail it. Batman '89 would probably look like Michael Keaton as Batman, and BB/TDK would probably look like Christian Bale as Batman, and not just be a reskinned version of the Arkham Bats. That's why I'd really like to see them do it.