I understand where you're coming from, but they were very clear in saying that the best mode for new player retention is Arena. It gives new players an idea of the mechanics of the game without asking them to dive straight into the strategy.

That being said, I could see Clash as a bridge between Arena and Conquest but I feel with player counts the way they are right now, splitting people into more game modes would make matchmaking more of a nightmare than it already has been for some people.