That's insane, amazing and so well deserved. The Last of Us is such a leap in quality in my opinion from the Uncharted series; the TPS mechanics, character movement, characterization, writing, story, you name it. It's true we don't know why Amy Henning and the others left Naughty Dog but if it was over radical changes to the Uncharted series in the wake of TLoU and Uncharted 3. I would consider their leaving a good thing, and furthemore if it leads to the next Uncharted having gameplay and writing of the same high quality as TLoU, the Uncharted series will be official saved from mediocrity.
The only reservation I have, is the 100 percent certainty of a TLoU 2. That game really didn't need a sequel, story wise it was absolutely complete with a perfect ending.
Oh well, I'm sure they will figure out some classy solution.