Season 7 is on track to be the worst season in League history. The plants, the ridiculous Krug and Raptor camps, and now the items and masteries.
Let me focus on the new tank items and tank mastery, Courage of the Collosus. With these at their disposal, tank supports destroy the competition. Say goodbye to all variety save for Alistar, Leona, Braum, etc. They just get so much HP for a nonexistent gold cost. It's also easily abusable for other roles that want to be tanky. Their invincibility at such early stages of the game remind of the dreaded IBG+SF tank meta. You just build health, have resistance in your kit, and CoC will make you unkillable before your enemies can even finish one item. Then you just kill everyone with base damage or zone carries by face tanking them.
Ranged supports will just get outscaled very quickly, and CoC denies so much aggression. I can't even imagine how bad it'll be for top laners.
Assassin meta? When the enemy has Heal, Exhaust, Locket, FotM, Knight's Vow, meathead unkillable bodyguards with tons of CC, and their kits in general, just how the fuck are we supposed to assassinate anyone?
I anticipate the meta shifting to tanks and champions that can kill tanks.