Seen here:
https://www.bleedingcool.com/2019/02/17/vampire-ghost-rider-avengers-15-marvel-preview/
This is a strong possibility since Robbie's GR is fundamentatlity different than Johnny and Danny's; this, not being connected to GR.
I predicted the slot next to Blade to be either Hellstrom, Jennifer Kale, Werewolf By Night, Man-Thing or Hannibal King, but this makes too much sense. Robbie isn't connected to Johnny or Danny, is part of the MCU and being a vampire, connects him to Blade.
If this does happen, I for one will be pissed. There is no way in hell (pun intended) Robbie should join before Danny. Danny made Ghost Rider what it is, and every GR incarnation that followed him has borrowed heavily from his look and persona.