Geoff said this about kon on newsarama during Rebirth talk.
It felt like the emotional connection I had with the character broke. I'll tell you a character specifically, and I'll be candid about it: Superboy, Connor Kent."
"One of my favorite characters of all time," Johns continued, "And I had a great time writing him in Teen Titans, and I loved writing him in his solo run [in Adventure Comics]. They reintroduced him in the 'New 52' and he was so different, so vastly changed, that I couldn't connect with the book that well. The emotional tie just severed, and it didn't sever in the way that made me angry, it was worse than that: I had apathy for it. I didn't care anymore."
Connor Kent remains absent from Rebirth, with Jonathan Kent, the son of Clark Kent and Lois Lane, advertised as Rebirth's Superboy.