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ArenaNet has put into place two powerful systems for responding to the needs of their own economy.
1. Black Lion Chests
2. Mystic Forge
These two systems can be adjusted and added on to in order to control changes in the economy. We have already seen this happen multiple times. For example, Halloween utilized the Black Lion Chests for festive rewards. I would assume that every holiday event will do the same. Then there were the limited time Mystic Forge rewards created in order to get rid of excessive supply on the Trading Post.
I do not believe that ArenaNet has any other systems in place that are capable of affecting the economy. That being said, there really is no need for anything else. The Black Lion Chests can get players to spend their gems if they get too cheap, and the Mystic Forge can be used to get rid of excess supply through gambling.
In fact, both systems are based on players gambling for extremely valuable items.
Can you make gold predicting the use of these two systems? Yes, I believe you can.