I think in some way the first is going to connect to Toral/The New World. The first trailer for Dawntrail makes an emphasis on Y'shtola visiting a Toral ruin that resembles Ronka from the first, which we know she studied very intensely in the story.

This I think will be the link, but how? There are so many implications if this is true.

Was Ronka first, or was Toral first? Most likely, it would probably be Toral if we are thinking based on how the first was formed. The first evolved out of a split of history. Everything in the first resembles the source, but only because of that one point of shared history before the split that was the sundering.

If Ronka was first, then that means the FIRST went to Toral, and influenced it in some way. Which might make sense, because Toral is very far away from the source. Why would the Great Ronkan Ruins be on the same landmass as Eorzea on the first, if they split off of Toral..

Perhaps Toral went to the first.. well.. first. (Bad pun) That could just as easily explain Ronka.. but who knows. It could go any way.