That will likely be the Aquaman trailer/presentation. Trailer will almost assuredly drop online simultaneously as well.
And if they bring Affleck out with Reeves, and finally, once and for all, announce/commit to The Batman along with a release date, I'd think that would go a really long way with fans.
Sounds like WB is going to announce the new slate as well (more Superman, Birds of Prey, etc.) and this does kind of feel like it could be a new beginning of sorts. No more Snyder, coasting off the success of Wonder Woman, etc. and things might finally start to look up for the franchise. We'll see, though.