James Gunn's DCU is bringing about a lot of major changes, especially where the looks of our heroes are concerned. A new Superman, Batman, and more are set to appear, but there will be some returning faces among this new cast.
Namely, as Gunn revealed on Threads, John Cena will return as Peacemaker, Viola Davis will once more be Amanda Waller, and Xolo Maridueña will continue to be our Blue Beetle. Also, it was confirmed that nothing is canon until after Creature Commandos and Superman: Legacy have released.
We may some familiar faces in between now and then, but otherwise their stories won't be considered canon in this new DCU. It's quite confusing, to be honest, but in a few years time we could be thankful Gunn is our new DC overlord. Or not. Only time will tell.