About Tidus…
Dream-Zanarkand should be gone. The Fayth needed to stop dreaming about it. However, Tidus can’t be jut gone - Japanese mythology doesn’t swing that way. What was, is. Tidus just wasn’t human, not exactly. He was and is a spirit of Zanarkand. He may, in fact, be hanging around there. He is still alive - but that’s just it. In the same sense he ever was. He never had a flesh and blood body except through the power of Sin. He was a spirit from the get go.