Many Hunter changes came with with Warlords of Draenor (which launched Nov 13, 2014.) This post covers those changes as well as the patch 6.1 tweaks.
Blizzard decided to do some cleanup on abilities and “button bloat” (too many buttons to reasonably use.) So they’re doing a little hacking and chopping and trimming and tweaking and… well, you get the idea.
They’re not revising the talent system this time around, or changing mana into focus, or anything that major. Generally it’s cleanup, reducing that button bloat, and so on. You’ll still be nearly the same hunter as before, hopefully just a little more streamlined.