Could Odium have placed bits of them on the moon and random comets meteorites ( what ever you call random rocks floating about in space )? So as to make it more difficult for the Shards to be reunited. Making Soulstone the meteorites that reentered the atmosphere.
I accidentally down voted this post.
But let's not go crazy and over compensate with the up votes, he only needs one. Let's avoid making him more powerful than he already is.
So with the Spiritual realm being not tied to a location. Does that mean that the Ideal fire is the same throughout the Cosmere?
In that instead of being a ( separate ) Ideal for Scadrial and Roshar they both use the same Ideal.
Oh, right. OK. No I don't think she is.
As for whether magic would dissipate if the Demons disappeared. I don't know. Because Arlen mentions that it is in everything.
I've also thought it radiated from the core.