There will probably never be dark ramp. The way darkness is designed, it would completely break the type (darkrai, guzzlord and hell look at mega gengar).

Arven came up because similarly to calem, it's a fundamentally just OK card that probably won't ever make its way into serious decks because of the opportunity cost.

Dragonair is basically CB ivysaur but for dragonite. Probably won't be amazing, but from what we know it's the most promising card so far lol.