Yes to keep using them you'd have to craft them or open them in those new 'Wild' packs
That's an excellent question. I feel like the brand new cards should be gifts to the players for their collection, since they aren't obtainable in any packs to speak of, anyway.
If they just take them away and say, "lol, just craft them" it'd be kind of a big finger up to everyone.
I would guess as we get closer to rotation and the new core set they'll speak of it.
Well, I've already stated how I feel about that, if that's really how it'll work out.
... something something greedy company.
I mean, if we're being pedantic it's not a big finger up to everyone, just to the wild playerbase. Not like standard players will miss cards they can't possibly use.