And if it didn't happen at all???
It's as good a question as "What if the Epistles of Paul -- or Peter --- are forgeries?" Various Reformation figures wanted to throw out James, some of John's Letters, Jude, the Epistle to the Hebrews (whose author is unknown) and even the Revelation of St. John.
What if the four Gospels were forgeries? They were all written anonymously --- none is signed or has internal attribution --- and the very earliest whole manuscripts (of books, not the whole NT) are from the late-3rd century and 4th century.
Why do I bring all this up? Because experts have evaluated the Ignatian manuscripts just as they have evaluated the Scriptural manuscripts. And you can find scholars who discount the Gospels or consider them hopelessly corrupted (Bart Ehrman, author of Misquoting Jesus; Jesus, Interrupted; God's Problem, and Forged, is just one example of a whole swarm of these skeptics.)
I do not say that the NT and Ignatius rise or fall together.
Neither do I say that the NT or Ignatius should be shielded from textual criticism.
I do say that nobody should be shocked that there will be writers out there who will try to convince you of the irretrievable textual corruption of ANY late-Roman-Empire texts.
By far the most --- which includes Catholic, Protestant, and Orthodox --- set aside 6 of the 13 available manuscripts as doubtful, and attest to the authenticity of the other seven Ignatius manuscripts known as the "Middle Rescension."
If you want to see some really interesting stuff here, check out Jaroslav Pelikan (d. 2006), a Lutheran scholar and historian (later converted to Eastern Orthodox) who wrote Development of Christian Doctrine.
Pelikan says it was Protestant historians who did the principal scholarly work that confirms the "Middle Rescension" manuscripts of Ignatius.
You'll find Pelikan very much worth your time.