It’s possible that he gets brought in for JL 2 if it happens. I’d like to see it if it’s a small role where he died and passed the torch to John Stewart.
But I’m glad he’s not showing his face in the post credit scene at the lakehouse. For a moment like that, I’ll always of the belief that it would ruin the warning. You got a large chunk of ppl at home laughing at his presence or simply freaking out because Ryan’s back. You miss dialogue, or miss how serious he’s trying to be. It’s much better to have Martian Manhunter calmly tell Bruce about Darkseid. Hal could be the one who told him off screen.
And why would Hal Jordan or a bunch of aliens know Batman or his identity and secret whereabouts? It just seems random. Much more logical to have Lennox come in as Swanwick/Manhunter passing off the info from a source, knowing Bruce will then take that information to the rest of the Justice League.