Another thing missing from Clash Royale but could be coming soon is Air Defense. Now this one is a toss up, as it would be a risky move that would only benefit in certain scenarios. However, the same can be said about many other troops or cards in the game. Everything has a pro and a con, or a counter. Many state this has been "ruled out" too, but we can't trust everything said at the forums.
Dealing with the Lava Hound, Minion Hoard, Bats or even the Electro Dragon can be a challenge. Of course, an Inferno Tower or Tesla can slow it down, but adding a dedicated Air Defense building would be nice. Not to mention help out with Baby Dragons, Balloons, and the Mega Minion. Or even hidden Air Traps like Clash of Clans. A hidden trap that's cheap and can seek out and kill air units.
The only way we see an Air Defense building being added is if more air troops are added to the game. We have the Mega Minion and Inferno Dragon. Those are two dangerous cards that an Air Defense could slow down. Even a Wizard Tower could be considered air defense, as it attacks both ground and air troops. I'm open to some sort of Wizard Tower. Plus, it feels like all they do is re-use troops from Clash of Clans anyways, so maybe we will get a tower of some sort eventually.
Or, even balance changes that make air gameplay fun again. Hardly anyone uses the Flying Machine, or even the Lava Hound anymore. Everything is fast decks, bait decks or beatdowns. We need a good middle ground.