I think one of the reason why mintpal or poloniex are not adding cloak on their exchange is because of the exchange anon function. This has never been done before and to their perspective, it is a big unknown. Maybe the devs are talking to them and explaining how the anon exchange function works, maybe they're waiting for this function to be tested and proven. who knows whats going on behind the scene?

I don't expect any big exchange to add cloak until the anon exchange function has been successfully implemented and tested.