Traders don't care about who's responsible for a hack. They only care about the effects on the market. We've clearly seen the hacker selling large amounts, throw in the uncertainty about whether you're going to be liable if you unknowingly buy any and it's understandable why people are steering clear.
Looks like the bottom has already been and gone. In a few months it'll be history and considering how brazen he's been I'll guess there's a good chance the hacker will be nailed.
I'm sure that soon or a later somebody will make a XEM mixer and slowly they will clean all coins.
Doubtful. XEM will never be the prime choice of your average drug dealer. The only way of breaking the link between coins is exchanges.