This year, we've got a Dragonlance movie slated to come out.
As Hasbro owns WotC - I think this is probably the REAL reason for yoinking the Dragonlance license.
Movies are a HUGE investment. Many don't actually make any real $$. We cannot forget that the fantasy genre spawned the likes of Final Fantasy and Lord of the Rings. From a strategic business perspective, I can see WOTC wanting to call all of its "storyline connected" product home.
As far as 4e - it won't even reach the development phase until at least 2020. WotC, in releasing 3e all but bet the entire COMPANY on that product line making a profit, including Magic The Gathering. You don't print millions of copies and spend all of those advertising dollars on 3 separate hardbacks lightly. There is no way we are going to see them take that kind of business risk unless they feel they have to do something to save their entire outfit.
As far as "Rules books" go - there are only 6 generic "kinds" I would think that make money.
1. The PHB
2. The DMG
3. Mosnter Manuals (maybe 1 per year)
4. Spell Compendium (maybe 1 per year)
5. Magic Item Compendium (maybe 1 per year)
6. Epic Handbook
In the case of items 1 and 2, half of each book is devoted to lists of spells and magic items, respectively. Accordingly, you could sell an "advanced" PHB and a DMG... but not much more than this.
What I would really like to see is WOTC sales data and the customer feedback that actually shows up to the WOTC marketing guys. I don't think we see the "Complete X" or "Races of X" books truly selling like hotcakes. If there isn't enough profit margin gained by investing the resources you need to print those books, you might want to move that kind of product into an online format.
I think we are going to see a move to an online subscription service for "module" based adventures - but not much else.
