Like how Garlemald "ended the cycle" of their oppresion in Ilsabard only to then turn their aggressive expansion onto Orthard and Eorzea, to which also started prior to their knowledge of primals? Hey, atleast Ishgard and Ul'dah have some common talking points to use when talking to each other!
As an aside with Zenos and for a possibly slightly different discussion, I have come to firmly believe that he is not being possessed by Elidibus (though there is a good chance of Asician foul play still being present.) I have also drifted towards being certain that Elidibus is infact possessing Regula...and the more further out theory that it is in fact like when Lahabrea possessed Thancred and its while Regula is in fact still alive. Even possibly that Regula had his life unintentially saved by being possessed. 5.0 will see us having to choose to either let Elidibus get away because we have means to defeat him but not permantly kill him, or we can take him out for a short time but be short a way to actually kill him once we have white auracite. But when we choose to go through with it we end up saving Regula, which leads to the WoL starting a good road to peace with Varis
Even in the case that this just saves Regula so he can die in peace that would probably be considered better by Varis then him being possessed so it could still have the same "possible peace in sight" ending.