I was thinking maybe Mera as Aquawoman (get her water control powers in) but Arion's a great pic. Hermes is a logical "God" pic for Flash, but I was thinking either a version of Zoom or someone from the Quick family. I keep thinking flash should be reliant on a formula or something in this world, it would seem to fit.
I saw someone somewhere suggest Sinestro as Green Lantern, which would be awesome, though the teaser artwork doesn't seem to fit that.