The cover to November's New Mutants #2 by Jonathan Hickman and Rod Reis appears to hint at the return of Kubark, aka Kid Gladiator.
Reis' cover art features the entire New Mutants team looking on as a shadowy figure appears before them. While the silhouette resembles that of Gladiator proper, it's more likely that it's Kid Gladiator since the series is centered on younger heroes.
The son of Gladiator, Kid Gladiator was created by Jason Aaron and Chris Bachalo and debuted in 2011's Wolverine and the X-Men #1. He was sent to Earth by his father to hone his abilities and it was there that he enrolled in the Jean Grey School for Higher Learning.
Here is Marvel's full solicitation text for New Mutants #1 and #2:
NEW MUTANTS #1 AND #2
- Written by JONATHAN HICKMAN & ED BRISSON (Issue #1)
- Written by JONATHAN HICKMAN (Issue #2)
- Art by ROD REIS
- Cover by ROD REIS
- THE NEW GENERATION CLAIMS THE DAWN!
- The classic New Mutants (Sunspot, Wolfsbane, Mirage, Karma, Magik, and Cypher) get together with a few new friends (Chamber, Mondo) to seek out their missing member and share the good news… a mission that takes them into space alongside the Starjammers!
New Mutants #1 and #2 go on sale in November from Marvel Comics.