Wait, so Ardyn is just "Ardyn", he isn't Nadir?
I think normal names have a place in the FF series. Maria(FFII also has characters named Guy, Gordon, Richard, Scott and Layla), Rosa, Edward(Gilbart in Japanese, though Edge's real first name is "Edward" regardless), Tina, Edgar, Vincent, and even FFXV's Iris(though had Stella remained, she'd also count). FF Dimensions has a Diana, a Barbara and a Sophia. But yeah, some normal names could fit. I'm actually surprised we haven't seen a FF with an Eric, a Tobias, a Mia, a Jessica(am I thinkin' of Lunar), a Sylvia, a Ray, a Luke(this was my preferred name for the Warrior of Light, now am I thinking of Star Wars), an Amelia, an Aaron, or a Raquel(like Rachel, but slightly different).
We see more NPCs with normal names. This isn't new either, as "first"
Stella was Bartz's mom in FFV, the King of Tycoon's first name was
Alexander, Edward/Gilbart's love was named
Anna, Locke's girlfriend was
Rachel,
Johnny had a crush on Tifa,
Marlene being Barret's daughter, and so on. Also don't mind the strange NPC names, like Zokk. Remember Zokk?
simple
assume bros died
regis died
nyx died
noctis and luna died
if noctis and luna can have a wedding in insomnia throne room we can assume there's an afterlife mirror image of eos and XV-2 can take place there
assets already there for the world too
edit: libertus can stay in real-Eos
Final Fantasy XV: After World