I can relate to Madmick on some level in that I didn't want Ellie and Joel's story continued. It ended perfectly for me. Then thinking about how they essentially had the entire world to explore, reading about the other survivors, it just seemed ripe to explore completely new characters.
That said, I absolutely wanted a sequel and there is absolutely zero chance I'd miss this game. Especially given Naughty Dog's track record with smashing their first entries in a series with a sequel.
The only way this would have worked would be to leave them; to go postmodernist, and fracture the narrative with a different perspective.
Imagine a sequel set in the world with other survivors. We experience the whole event all over again, and the trauma suffered by our protagonist.
Fast forward. He/She is surviving in this world. We establish a close relationship with someone very dear. Maybe this person saved our protagonist, and taught him how to survive. They live on the outskirts. They avoid the oppression of the government that reigns. This mentor is a leader. He is a good. He is someone who instills hope around him. He makes life in this miserable hellhole worth living. Always sees the bright side. He is someone we believe could help change the world. Eventually we learn...this guy chose to become a Firefly. His great mission in life, and now also that of our protagonist, it to find a cure to the disease.
Then, in the first mission in the game, which sees us as the protagonist disembark with our mentor on a vital quest towards this goal, our mentor is bitten. We drag him out alive-- barely escaping some monstrous horde by the slimmest margin. Now, this person, the center of our world, is comatose. It's only a matter of time before he is gone; succumbs to the disease. We are crestfallen. It's the end of our world.
Then, through the grapevine, we get the only sliver of hope we've ever gotten. There is a rumor there is a girl who is immune. She could be it-- the great redemption, the cure. We hear the Fireflies have already begun to smuggle her to a hospital where she will be studied. Time is not on our side. We need to help her get where she needs to go. We need to get to the hospital. We need to get the cure ASAP.
Off we go. At points maybe we play a role, unbeknownst to Ellie and Joel in the first game, that was vital to them surviving on their way to the hospital. Ultimately, we arrive at the hospital. We learn the truth. To our horror, we discover we got there hours or even days too late. We learn that the man who guarded the girl murdered dozens of fireflies, and stole the girl away, rather than sacrifice just
one measly life towards a cure. We are enraged.
We have a new quest. We are going to hunt this man down, kill him, capture the girl, and return her to the Fireflies in order to find the cure so that we can return and save the person who is the center of
our world-- the one most dear to us. Not this Ellie.
Maybe once you find Ellie you tell her the truth. Then she learns that Joel was lying to her all along. Does she choose to go with you or her own volition? Do you kidnap her? We all know either way that once you do you will be fleeing Joel who is hunting you down to get her back.
Think of the possibilities for narrative choices this would present. Suddenly the person you played as the protagonist in the first game is the great antagonist in the second game. Can you change Joel's mind? If you don't, what do you do? Do you seek revenge for the sake of revenge?