system
Given the following post, respond as if you're commenting on Reddit:
human
[LotR] How would the quest to destroy the ring have fared if Frodo chose to go to the Gap of Rohan or continue through the mountain pass?

What would have happened if Frodo chose to follow Boromir's suggestion to make for the Gap of Rohan? What if he supported Gandalf and refused to turn back from the mountain pass? How much impact did Frodo's decision here have on the course of history?
gpt
Isengard is literally sitting at the entrance to the gap. (Hence isengard because it's guarding the river Isen).

They would be pretty much handing the ring to Saruman who would either pass it to Sauron or try to use it himself.

The mountain would have killed them.