You are aware what a meteor that big would do IRL, right?
It's what, 700 ft up? And it is mostly hollowed out. Yes, it would go THUD and squish the canton into the bedrock, the impact would displace the water and cause flooding; the physical impact would cause serious structural damage to the other cantons. Would it shroud Vvardenfell in a post-apocalyptic haze? I doubt it.
EDIT: M'Aiq, the Cosmology section at TIL mentions that Masser and Secunda are disintigrating -- like, parts are fading away. I don't think they are going to fall down...