Some historical sources claim that Nestorian Christians were actually outnumbering Zoroastrians in the Sassanian Empire by the time it fell to the Arabs.
So, given that the Sassanian Empire would have survived the surge of Islam (maybe if no war with the ERE had happened), I think it is not ASB to foresee that Nestorian Christianity would had finally imposed to Zoroastrianism if the Empire would have lasted some centuries more.
Which could have been the consequences for the ERE and the rest of Europe if a strong Persian Empire would have survived and later officially convert to Nestorian Christianity as the state religion?
So, given that the Sassanian Empire would have survived the surge of Islam (maybe if no war with the ERE had happened), I think it is not ASB to foresee that Nestorian Christianity would had finally imposed to Zoroastrianism if the Empire would have lasted some centuries more.
Which could have been the consequences for the ERE and the rest of Europe if a strong Persian Empire would have survived and later officially convert to Nestorian Christianity as the state religion?