Be sure to read part one of the professions post for the strongest and weakest professions, plus a word on gathering professions.
In addition to the Mists-Truegold, however, you'll also have gem transmutes. If the cooldown remains off, you can transmute as many common "green" quality gems into rare "blue" quality gems as you can get materials for. This will help your Jewelcrafter make even more gold (if you have one) or still turn a tidy profit selling the gems to other Jewelcrafters.
Potions, especially healing and mana seem to be in decline in Cataclysm (no health/mana pots drop from mobs), thought they've remained profitable if you're a good shopper for raw materials. I'm uncertain what to expect from potions in Mists, but I think they'll continue to be small profit items overall compared to other markets. Flasks could see a surge if the guild cauldrons aren't updated to Mists-level buffs. If they are, you'll likely see a surge at first, then decline as guilds get their people leveled and stocked with cauldrons.
Recommendation: Because of the daily limit on transmutes, they will remain extremely profitable throughout launch and into the 2nd content patch. While the initial leveling at launch may be high, there's probably enough profit to support 3-4 alchemists. If you're looking for a good pairing, Jewelcrafting and Herbalism are good partners for Alchemy.
There will be money in creating Darkmoon Decks and Cards. Darkmoon trinkets have historically been best-in-slot for the first tier of raiding in an expansion, but have often remained strong contenders into the 2nd and even 3rd content patch. Mists should be no different as people look to spend some of their amassed wealth on top-level trinkets. Expect to burn through a lot of herbs creating the cards, as well as doing lots of wheeling and dealing with other scribes for the cards you're missing, but the payoff could be huge. Darkmoon business alone could get you to the gold-cap.
In addition to the decks, expect a surge in Mysterious Fortune Cards due to a shortage on the market. Blackfallow Inks will be in short supply as the farmers rush into the new content and Mists-level herbs. While the Mists-level herbs can be down-converted into Blackfallow, they'll cost significantly more. Smart scribes (and non-scribes for that matter) will stockpile Blackfallow Ink as well as MFCs for sale after the supply dries up a few days or weeks into Mists.
Recommendation: One scribe will do. Books of Glyph Mastery and research are the current limiting factors on Inscription. You'd be insane to want to do that more than once.
You'll also want to craft and post some rods for enchanters to use right at launch. Be the first to get some up and you could command a premium price. Enchanters will need a new rod in order to start leveling their profession and making the new enchants. You'll want to supply them.
Tank Plate and all the weapons are traditionally strong sellers for Blacksmiths as well. Guilds will want to outfit their tanks as quickly as possible to begin running heroic dungeons and raids. Tanks are usually among the first to get guild support for gearing and enchanting, so you should see some strong sellers here. Weapons of any kind can be the most difficult and painful slot for people to fill, usually because there's strong competition for them. They also are responsible for some of the biggest DPS gains, so people are going to want them. You'll likely be limited by the number of Mists-Orbs (like the current chaos orbs) you can obtain, should Blizzard keep the existing paradigm of them dropping from dungeons.
Recommendation: One Blacksmith is sufficient.
Tailoring should continue to see profits into Mists of Pandaria with the leg enchants for casters, as it is currently the only source of the enchant. The smoother upgrade path of Dungeon/Heroic/LFR/Normal Raid/Heroic Raid will help keep a steady supply of upgrades flowing.
Another point in favor of Tailoring is the bigger and better bags that will arrive in Mists.We'll almost certainly see one larger than the current Embersilk Bag and wealthy pack-rats everywhere will rejoice at paying a steep premium for 2-4 additional slots in their inventory.
Recommendation: One tailor is sufficient, though a 2nd could be beneficial for the first tier of crafted items if there's a similar cooldown to Dreamcloth in Mists.
Also like tailoring, this is the only source of leg enchants for melee classes, so there should be a steady supply of income from them as well. Mining bags in the early part of Mists should be strong with the added number of people farming to take advantage of the initial surge in prices, but should taper off quickly after that.
Recommendation: One Leatherworker is enough, but don't worry if you don't get there.
If I'm ranking all the professions and putting them into slots on a character heading into Mists of Pandaria, I'd go with the following order:
1. Jewelcrafting / Alchemy
2. Enchanting / Alchemy
3. Inscription / Herbing
4. Blacksmithing / Mining
5. Tailoring / Alchemy
6. Leatherworking / Skinning
One caveat to this is that you might consider going Inscription / Blacksmithing in slot 3 so that slot 4 can be a dedicated farming Mining / Herbing alt that you use for the first couple weeks.