I have said it many times before but it needs repeating. DC are idiots for not sending Chris Kent (Lor Zod) to the future and making him the full time Superboy of the Legion of Superheroes. It would give the Legion writers a Superboy of their own that they have total control over without having to worry about what is going on in other Super-books. It also opens up so many story avenues such as Mon-El taking on the big brother role to young Chris or Chris having to deal with being the son of one of Superman's greatest foes. It would be so easy for Mon-El and Braniac 5 to pull the kid out of the Phantom Zone. Maybe even have him aged up a few years so he is in his mid teens so he could be the young kid on the team.
It jut seems like such a no brainer idea and the fact DC never went with it and instead just dumped him into the Phantom Zone forever makes no sense
Jon is going to be the one and only Superboy for the forseable future that is just a given. I could see them bringing Conner back but he will not be called Superboy. I am not sure what new name they will give him, but it will not be Superboy. I think every character needs to have their own identity and name so I don't want 2 or 3 Superboys runnning around the same time period.