The WoL canonically has been shown to be a very stupid individual and tends for better or worse to be a murder hobo continually stacking corpses wherever they go.

I wouldn't expect Yshtola to ever die. It's Yoshi P's waifuu and poster girl for XIV. Her premiere inclusion in Dissidia NT, a unit in DFFOO, multiple Mog Station outfits, a play arts Figma, a minion statue and a $1000 Dollfie dream lifelike doll make Yoshi P some big bucks that killing her off probably isn't going to happen.

If anything Grandma Matoya will be the first to go due to the characters old age.

I wouldn't be surprised if Matoya restores Yshtola's sight and lost life force as a final parting gift.

Rendering all that hoshposh about decreased lifespan a rather moot point.