For the new Kyurem forms, their effectivity in OU really depends on how it's typing will be affected, if it gets an ability change, what moves become available to it, and (if tutors are instated) how those move tutors will affect Kyurem's usability. It's too soon to speculate, as none of these aspects are currently known. I suspect however, that Kyurem will become OU because of these forms, allowing it to be used outside of hail if its typing does change.
Tutor-wise, we could see some Pokemon jump tiers, as we normally do. If Haxorus gets Fire Punch, it may get the boot up to Ubers just because of how easily it'd be able to bust up the metagame.