Hey, can I say something on the pessimistic side? I'm currently in a long term relationship. I like dominant women. She is not one. Our solution? Have worse sex, less often. I don't believe your wife will ever be a great domme because she wasn't born one. I don't care what people say, the best sex is sex that brings out the animal in you- the innate urges. If she isn't innately a domme, her attempts to be so will never be of the highest possible caliber. They'll be bland, and you will detect her boredom. There are plenty of girls that pick up a whip one night and have some fun, but there really aren't that many by comparison who live by the whip, and while she MIGHT enjoy the novelty of her dominance at first, I have confidence that if she wasn't born into loving authority, she will tire of it.
It's hard for me to say all this, because i know the misery of unfulfilled urges first hand. I would love nothing more than to be proven wrong and for you to say how great a time you and your wife are having.