Man, did you hear those people scream at those reveals?
While I don't think we needed a sequel to TLoU, I'm not upset. It's not like Naughty Dog made the original end on a cliffhanger just so they could make a new game, like Ubisoft does. It's actually the fact that TLoU was a self contained story that I am fine with a sequel. That may seem counter-intuitive, but whatever.
As for Joel and Ellie being in the game, I'm also fine with this. While other characters could have their own roles in the story, and likely will, I'd at least want them to make an appearance for obvious reasons. But the main reason TLoU was so good and memorable was Joel and Ellie, so it makes sense to have them in it. Joel and Ellie are TLoU. Making a sequel without them would be like making Justice League without Batman or Superman.
At the end of the day, this is Naughty Dog. They probably have the best record of any developer out there. They're like Rare back when Rare was good. So that's a good pedigree even without the previous game's reputation. I may be odd, but I'm confident the game will at least be good. The question is, will it be great? Will it be able to live up to it's predecessor's legacy? That's almost why I'm worried for it. TLoU2 could be the best game of the year and still be seen as a failure if it doesn't deliver what TLoU did.
Anyway, I think I can sum it up with a picture.