I doubt Supercell is worried or sadden at the moment.
You gotta remember that the update is pretty new, just a couple of weeks out. The extreme gemmers are gemming a lot to get to TH11 and access to it's perks. Even if some players desist to buy gems, the top gemmers are just overwhelmingly filling up for their losses.
But I agree with you, after all this TH11 hype passes, Supercell will face a drop in players and probably gem purchases. And I hope it makes them consider that disappearing from the radar in difficult times doesn't do any good, and that it's a complete disrespect to their loyal costumers.