I'm pretty sure the "people can still be turned into blasphemies" bit is a Doylist answer for why the Role Quests are still a thing after the completion of the MSQ. I'm not expecting them to have any presence in the future.
Between all the hints Emet-Selch gave us in Ultima Thule, I'm honestly not sure where things are going to go from here. That said the only hint with any weight I can think of is Montichaigne's lecture on the memory erasure of the Seventh Umbral Calamity's aftermath, and that Lorens (the erstwhile commander of the Company of Heroes) promises to meet you again after the Melee DPS role quest, but comments he might not / probably won't remember you due to his flighty personality. That and Corvos is mentioned a lot, so.