I’m really hoping Water, Earth, Light/Holy, and Darkness (especially since the early leaks showed Darkness was briefly part of early builds of the first installment) get added as elements to future installments’ gameplay, feels weird for Leviathan to be a non-elemental summon.
Also would be cool if Summons get regional variants (like how Bahamut had upgrades in the OG) like a Wutai version of Leviathan, or a Northern Continent variant of Shiva, a furry/beast version of Ifrit for Cosmo Canyon, and maybe a “modern” Shinra version of Alexander paired with an Ancient Cetra version of Alexander, etc.