tiny, non-zero chance that it would have been a 90-yard TD pass. Without the defensive holding, it was more likely to end up an incomplete pass or a sack than a 90-yard TD pass, IMO.
However, it had a decent chance to being a 10-15 yard reception, which is what BYU desperately needed on that play. Regardless, it was a clear penalty and the officials got it right. That's all that really matters.