If you're not planning on leveling alts and you don't foresee yourself affording the mats from the AH, you might consider grabbing a gathering profession that works with your crafted prof. If you have alts you're already planning on leveling (soon) you can probably leave your current professions as is. Personally, I'm sticking with LW/Skinning as that's what I've been on this hunter but I'm also looking to level some alts for herbs to help with raid materials.

Alchemy should always have a strong economy with pots/flasks. Now professions like JC will always be useful due to the chances of gem slots, but the market might be volatile if you're looking to sell them. However, the current cap on crafted gear is 850 (which might increase over the course of the expac as the obliterum mechanic sets up nicely for that) so after heroic Nightmare crafted gear is gonna lag behind, which the devs said was the intention. For example, for a hunter, leatherworking is really nice because you can farm as you quest and make your own gear/upgrade it. If you read the spreadsheet that Effin posted it shows the weight of how the professions help in gearing up. I'm in the exact same boat and want someone to tell me what to do.That's just it, no one can tell you.

Best professions for hunter legion