I heard they were making the Justice League movie with motion-capture all-CGI, ala The Polar Express and Happy Feet.  In fact, I think the director of Happy Feet is actually helming it.
If this is true, and with it being all of the superheroes together, I don't think the general public will have a a tough time discerning the film from being in the same "timelines" as the current Batman and Superman films, so I don't think having different actors would be a problem.  Also, if the CGI thing is true, I move they bring in Kevin Conroy as Batman.  Would that rule or what?