This is what I'd like to see happen. A full-fledged JSA show launches with the founding members from Arrow being being Atom, Black Canary, Flash, Green Lantern (John Dingle/Stewart), and Wildcat.
Ollie should cross worlds in the last season of Arrow and bring Black Canary back from the dead, with the help of Dr. Fate and The Spectre. He should sacrifice himself and take her place in the grave to do this, then get resurrected on JSA with the goatee and a new perspective... less brooding and more spiritual.
The Spectre and Dr. Fate stay on JSA as series regulars. Maybe Ollie's journey back to life has unexpected consequences that only they can deal with. When Oliver dies, Thea honors him and takes up the Arrow mantel. Speedy's TV persona gets merged with Artimis Crock to become Green Arrow. When Ollie comes back to life she gives him his mantel back and he honors her by keeping the name.
Speedy then joins the cast of Teen Titans to be with Roy Harper, who leaves Oliver's side to become a founding member, and also serves as a JSA liaison through his direct connection. Kid Flash should be introduced on Flash and sent over to the Teen Titans as well.
Supergirl's series introduces Stargirl and Hawkman who then join the JSA ranks. Star Sapphire could have her introduction on Supergirl as well before joining the Titans. Everyone cameos on big cross over events and they stay clear of JLA's feature film shadow; while kicking separate but equal ass on TV. Nobody gets their toes walked on as long as JLA's Flash is Wally West and GL is Guy Gardner.
There should be a Legion of Doom featuring Vandal Savage, Grod, Reverse Flash, Solomon Grundy, Deathstroke, and other's who serve as the organized force against JSA. I don't think Snyder is going to camp up his series enough to accommodate the Legion by name or with these characters.
