Its now quite obvious that Games Workshop has certain Primaris Marine characters coming soon. Both an Apothecary and Chaplin are listed on the new transfers.
Link here to see the new transfer sheet yourself.
https://www.games-workshop.com/en-GB/Primaris-
As readers have seen this online, they have sending emails that this is just one more step to replacing normal marines. (Something I don't expect at all during this edition).