This is just speculation, of course, but given how key Hippolya is to the Wonder Woman mythology, her presence is welcome.
Since Wonder Woman doesn’t arrive in theaters until next June, all we’ve seen so far comes from Connie Nielsen’s Hippolyta comes from two trailers, where she’s heard warning her daughter to be careful.
However, a photo released earlier today came with information that during the first act of Wonder Woman, Diana will disobey Hippolyta by breaking into the armory on Themyscira and stealing the “god-killer” sword so she can be properly armed to help humanity during the Great War.
It’s possible that due to those actions, Hippolyta was forced exile Diana and prevent her from ever returning to Themyscira, meaning that Justice League will be the first time they’ve seen each other in 100 years.