Sony's Chris Ashimine not sure if next Naughty Dog game will be Uncharted, but it will be on PS4
After the 3 main games, a digital comic, a novel, a Vita game and a turn-based card game I don't know if I want too see more of Uncharted... UC1 is fine as a game and it has nice moments, UC2 was a great and UC3 expanded on what UC2 did while making the multiplayer more fun (and messy).
Best thing Uncharted 4 could do is be prettier, expand the gameplay a bit more and continue the story of Nathan Drake (even though UC3 give a pretty nice "farewell" kind of ending).
A sequel to The Last of Us is kind of a weird situation. They can make a sequel set a few years later and what not, but the entire narrative of TLoU and the reason for why that game even exists is mainly because of the experience the main game already provides, which a complete experience that doesn't really leave you with the curiosity or need for a sequel, and with that in mind the whole thing with TLoU is "over" outside of the single-player DLC Naughty Dog has been working on (and that's a side story).
So yeah. I personally would rather see Naughty Dog starting fresh on PS4.