I've never been so deeply involved with a long epic when only the first book was out before. I'm having lots of fun theorizing. Even if most of my theories are probably going to end up being wrong.
from Dalinar's last vision it seems to be the threat of total destruction. Which makes me wonder why Odium apparently wants to destroy Roshar so badly when he didn't destroy Sel even after killing both the known Shardholders there.