I reckon the drive to buy energy packs with money will go down, which means bad profit for Three Rings.
Perhaps some rarities and crowns fixed for each purchase or constant mini-promos would help maintain a healthy profit? Mini-promos I imagine would be a 5* item of choice, or such things, which switch out every once in a while, in addition to the main promos which come now and then, bringing entirely new content.
Also a long haired helmet or accessory would be nice, for a random thought.