More on Tradeskill Changes
It looks like the changes are more sweeping than I originally thought. For example, the Geomancy book from Tier 2, which everyone can buy and use, contains recipes not only for Stroma Wash, Stroma Oil, Stroma Resin and Eolith Temper, but also for Trinoid Reagent, Iron Gual Dye, and Iron Gual Ink. Wow.
As a Jeweler, I can now buy the Geomancy book and make my own Iron Spike to use in making Runes. I am not dependent on any other class to make Runes. That's kind of a shame, I liked that aspect of it.
Sages are now highly viable, since Timbercraft Essentials 1 contains recipes for Cailun Paper, and Maple Quills. Remember that all artisans have the Timbercraft skill and it increases automatically with level.
Personally, I'd recommend giving all artisans the skills but not making them advance automatically. So you could allow specialization, but not require it. If they start gouging you too much for your supplies, then you'd do it yourself.
Here's some screenshots of the books, and the new reaction arts that go with them, thanks to Anya Foodcrafter.