Kurotowa
Legend
From an in-universe perspective, we don't know if warforged age or not. The oldest is only like 30 years old. That's still the prime of their life for many humanoids, and early childhood for others. Maybe the wear will accumulate and they'll break down after 100 years. Maybe after 300 years. Or maybe they really can keep going indefinitely, barring injury and with good maintenance. No one really knows, and the only way to find out is to wait.Theoretically they're immortal. Last session the players encountered a giant pike. This turned into how old are sharks. 450 million years they're older than trees. See where I'm going with this?
I'm not such a fan of watforged and immortal races. They can be killed but what if a group of them decided to try and survive for a really long time?
It's an interesting open question, and I have an unused PC stashed that's a warforged adherent of the Blood of Vol who is very focused on it. Is he basically like the undead martyrs, an immortal with an artificial soul and synthetic blood who has no divinity within and can only be a guide for others? Or did the Creation Forges have secrets beyond what Cannith knew, that they plucked the spark of a true soul and filled his veins with blood as true as any other, and as an ageless Seeker he's better positioned to fulfill the aspirations of his faith than any other? Or is he as mortal as any other, with an uncertain life span that will sneak up on him with no warning?
If the DM wants to make a declarative ruling, that's fine. But in-character no one knows the answer, and that's great story fodder.