I mean, if they aim for something like Crisis on Two Earths and Justice League: Doom, I think it should be fine since those were both pretty in-line with the original tone of JLU and the DCAU as a whole.Honestly? I don't want any potential JLU reunion movie within five feet of these hard PG-13 / R movies. That ways lies Batman and Harley Quinn. I want whatever JL reunion we someday get to be consistent in tone with the show I loved in the first place. Part of why I loved JLU was because it was kid-friendly and fun. If they use the DC Universe movie label for a reunion, it probably won't be.
Put it under the DC Classics banner like Return Of The Caped Crusaders was. That had the potential to be an amazing banner, and they dropped it after two movies, and didn't even label the second one with it.
I don't want JLU back with blood and swearing. That's not the reason I loved the show. I loved the show because it DIDN'T have that.
Granted, I think a lot of that had to do with the late great Dwayne McDuffie being the screenwriter for both films (and CoTE was a repurposed script to begin with), but it still indicates that it's feasible with the right writing and awareness of what the movie is trying to be.
Like with a lot of Timm's stuff as of late the quality is probably going to be very dependent on his collaborators and who's handling the writing.