Hal Jordan is pretty much guaranteed for second part. Martian Manhunter, maybe as a plot device later on at final part. He is one of the powerful figures of JLA sometimes compared and even above Superman. I believe he will be more like Vision from AoU, since Mars already most likely got invaded by Darkseid already.
Blue Beetle, Green Arrow, Black Canary and Zatanna are not very likely in my book. The movie is titled JLA and most focused on facing an unstoppable force against all odds. In fact, I believe there is more potential to JLA after Darkseid saga. Maybe a sequel about Nekron and Black Lanterns, then they may add more characters like Oliver and rest.