Zoroastrianism is on the way out because it refuses to accept converts. One has to be born into the faith to believe in it. In contrast, every other religion welcomes those from outside to propagate and spread the faith.
?....Are not the 'converts' to Bahai.....considered.....Zoroastrian?
The perfect answer is Christianity. I suspect that the "wise men" from the East who came to the manager to honor Jesus were Zorastrian. That faith has a messianic theme. I have long considered Christianity to be "fulfilled Judiasm". I wonder could it be considered fulfilled Zorastorianism too?
In a brief look at some Zoroastra sites I could find nothing to support the comment about their not accepting converts. It appears they do. I believe the wording in the article was in relation to the Moslems not allowing converts out of Islam. That seems to work better. The tree and the statement above link to ZA sites.
The text suggests that Zoroastrians refuse to accept converts because they do not want to be exterminated by the Muslims for accepting converts. It would follow that if they do not have to fear the Muslims, they might change this policy.
This is true of the Parsees from India and has historical overtones. When accepted there as refugees by the ruling Hinuds, they required them not to proselytize.
Zoroaster actively sought converts, as did his immediate successors.
The Persians Zoroastrians are more open to converts, but again, their reluctance to actively proselytize is the product of Centuries of Islamic oppression (death for those who seek to convert Muslims).
At any rate, Zoroastrians, unlike Muslims, do feel any compunction to forcibly those who do not wish to be Zoroastrian.