Sharlayan, I feel, is a strong contender for the future of the story. As others have alluded to they are isolationist and we've only had hints to what there culture entails from dungeons and their colony in ruins in the Hinterlands.
But, note names of the areas associated with Sharlayan in those dungeons and open world areas are Greek routed words. I also noticed when we arrived in Amaurot, interaction with the npcs during the few side quests in the area often allude to the "Sister City" while their areas and dungeons associated with the ancient Ascian culture also go on to be named in Greek routed words. If you really pay attention this done very heavy handily in both Amaurot and Sharlayan places.
Lets not forget that most of the scions are linked through their back stories to Sharlayan. The twins and their grandfather are from an important family in Sharlayan. Y'shtola, Urianger, Moenbryda and others are educated either directly in Sharlayan or in the Sharalayan tradition.
Sharalayan is isolationist, that is for sure. But I think the ground work has been set up to show they are hiding something, most likely knowledge, not withdrawing from the world politically to preserve their country. They are, and this my feeling from the observed information and the story so far, the Hydaelyn fraction of the ancients and hold the answers to the next set of questions. The capitol of Sharlayan is the Amourot "Sister City" and all our favorite people are tied up with them.
I know many people have speculated for a long time that 5.0 and now 6.0 has to be the invasion of the empire, but they are the red herring. I believe the person we need to be watching is the person in white robes who is with Zenos (the white robes themselves a red herring too).
