If Ashitaka is right, and the Iron works and the forrest can live in peace, the movie doesn't do a good job of explaining how that would work.
Are the iron work folk gonna stop making iron? Do they have a method of getting the iron without cutting down the forrest? Is it just that the forrest is so weak due to the ending of the movie, and basically clear cut anyway, that the humans won by default?
It's strongly implied that the forest will return, but nothing has changed.
Like, just give me a scene where Ashitaka shows them how to tunnel a Mine or something. Maybe a "we'll help to replant the trees after we cut them down" from the iron folks. Anything.
I think the uncomfortable ambiguity might be intentional
reminds me of the ending of another Ghibli film, Pom Poko, where people and nature do not learn to live in harmony, nor does one wipe out the other, but instead they settle into an uneasy synthesis
though Pom Poko is much less optimistic about it than Mononoke is, as I remember