as far as I'm concerned mango is now a core item on every hero.
Is it pretty safe to assume that there won't be a new hero with this patch? Each other time they usually announce it with the notes themselves.
I don't think it's core on every hero, it's more like a poor man's mana boots. Honestly it's a major change to support. Mids will still buy bottles, but if supports need something in the early game they might carry a mango or two. I think this does represent some changes in the 4 and 5 roles, namely the 5. They will have to "walk on eggshells" a little less and can be a bit more active, especially if they have mana hungry spells. The way I see it, it's more like this.
4 - Mana Boots and Mek > new boots
5 - Wards, use 4's mana boots if needed, mangos if you need them.