To be fair, we do have an established precedent of near inaccessible areas abruptly opening up as and when the plot demands it. As I see it, there's a number of possible options including:

- Krile successfully makes a case for the Forum to make an exception to their established policy.

- Krile fails to convince the Forum and we look elsewhere for information and allies to work with.

- Krile fails to convince the Forum but we infilitrate Sharlayan somehow.

- Krile fails to convince the Forum but our character ends up attacking Sharlayan. (I mostly bring this up because it'd echo Cecil's invasion of Mysidia, though I'd be surprised if such a route were to be taken.)

- Something dire happens to Sharlayan and makes it completely inaccessible. (Unlikely, I think.)

- Something dire happens to Sharlayan and that is why our character and the Scions go to visit the place.

At the moment I'm 50/50 as to whether or not we go there during the expansion. There's certainly been a lot of build up towards the place and if we're after ancient knowledge and/or power then it does seem like the place to visit for that.

I also wouldn't be surprised if the isolation policy was due to thorough knowledge of the Source's true history. Here's hoping that such knowledge gets uncovered and spread far and wide.