Surprising I'd bet no one, the introduction of a progressive gold cost for switching specs will be removed from the Legion beta. However, this doesn't mean we're going to be seeing everyone swapping out talents and specs on every fight. Here's how the second 7.0 spec/talent switching system is going to work:
Specs can, I believe, be changed on the fly (if you played before Mists of Pandaria, the terminology of "Spec" and "Talent" is sort of entangled, so it can be confusing,) with the current restrictions (must be out of combat, must be able to cast for ten seconds.) You'll have access to all the specs of your class. As far as I can tell, this aspect is practically the way that it works today, but with a "tri" or in the case of Druids, "quad" spec. (Demon Hunters will of course be dual-specced.)
Talents, however, are going to be more restricted. Currently, you just need a Tome of the Clear Mind to swap out talents. In Legion, the current plan is that you're going to have to give them a bit more thought, because you'll only be able to change them if you are in a safe area - namely anywhere that you'd get a rested bonus. So your Order Hall, a City, or an Inn are all places where you can trade these out, but otherwise, you're stuck with it.
The exception is that if you get an item created by a scribe, you can drop it for anyone in your party/raid to swap out talents outside of these safe locations. You will not have to be a scribe to use these items, only to craft them (which should help scribes make dough now that the glyph system is getting overhauled.)
I honestly think this is a pretty good solution. You can live with non-optimal talents if you switch from soloing to group content or single-target to AoE, but being able to change specs will make a huge difference for things like world bosses and group quests. Especially given the rumors I'm hearing about the nerfs that tanks have received, I really don't want to have to solo as Protection.
Still, we'll have to see how it feels in practice. While I absolutely don't want to return to the vanilla style where you basically got gutted for gold if you wanted to tweak any tiny thing, I also think there ought to be some encouragement to put together a talent build that suits your playstyle. And of course, I'd assume that switching specs will grant you a different array of talents.
I'll be watching this situation closely. 3.1's dual specialization feature was, I think, one of the best things introduced to the game, and I hope they retain at least a system that lives up to its functionality.