Maybe it was a permanent Jutsu.
Maybe it'll grow back soon since Obito is defeated, I mean it took the 3rd Hokage a while to regenerate.
No one knows.
Well edo has already been canceled, just because Obito doesn't have it now doesn't mean he can grow his arm back.
Onmyndon is a ninjutsu
So it's effects should wear off
Yes he'll regenerate if he's edoWhy? If a character gets hit by - let's say -, a fire ninjutsu, and the caster is defeated, does the wounded one Regenerate because of that? Hardly...
Since Hiruzen regenerated, it should grow
Why is minato's hand still cut? since the whole "omnydom" thing is over and he's an edo.
Yes he'll regenerate if he's edo
arm (10 char)