Oh, that's an excellent, chilling ficlet; killer last line.

I don't believe this, because I just don't think there's any evidence that Y has anything to do with what's happening to Dean right now.

I think you may be overestimating how much store the writers set by clearly linking plotlines and their consequences. :p I've been suspecting for a while that Y will happen, and I won't mind if it does, but I'll probably be pleasantly surprised if they go with something a bit less obvious.