It's on Reddit and on his twitter. Just scroll. It's in this month.
I'm not saying anything like that is going to happen to Damian . I saying that WB not DC is the one that seems to backing Damian the most. They are/were more invested in the character than TPTB at DC. If that's still the case then it really doesn't matter what the TPTB at DC or star writer want. It's the Synder/Duke/New Robin thing all over again. DC approved a new Robin WB vetoed it and brought Damian back.
Personally though i do think that Damian is going to graduate the role and Tim will stay Robin. Not sure about Jon though.
Nightwing and Flamebird might be a thing. We saw Damian as Nightwing in Dick's visions, According to Rebirth nightwing Damian is the heir to Nightwing. and if Dick was going to pass his mantle to anyone it would be Damian.
However I hope it's not because I don't think Nightwing is a mantle that should be passed around like Batman or Robin [yes i know it's origin and that there's been more than one but I can't think of anyone as Nightwing but Dick]
However