Two things need to happen, imho:
1- make professions trainable to max level from past expansion (IE 450 during Cataclysm, 525 during Pandaria) for a large gold sync. You don't train any of the formulas, you just get your profession at that level. Let's say 3k for 450 and 5k for 525.
Like this you add a gold sink, you let people not use it if they don't want to, but it's there for those who want to burn the cash and save time.
2- leveling professions need to be interesting. And how to make that happen? Imho there needs to be an array of patterns that are drop-only, or quest-reward only, and these patterns "reward" you for going out in the world to find them, because they either: stay orange for longer, are cheap, or give you several points at a time, like the most recent ones. That way, if you pick your professions and level them while questing, you're rewarded. If you do instances, then they drop, and you're rewarded for playing the game instead of mind-numbingly sitting at the AH buying mats and clicking like a moron.
