I was not expecting this, but a reader here emailed in to GW customer service and got a reply on who can take Imperial Knights as allies. The answer was any 40k army......I still expect something along the lines of a codex of sorts to come out this month, that clears this up as well. This definitely gives some good insight though into what may be the direction its going to go.Here's a reply I got from GW Customer Service regarding the key question, can Chaos ally with Knights?