I'm bad at multiquote, so here are some bullet points about the previous posts.
- Ellie's redemption already happened. When she had Abby for the kill, she remembered her last meaningful conversation with Joel and realized she was wrong. She learnt from it and moved along. That's her true ending.
- She's not the protagonist of the first game, where she's a passive plot device that only becomes a character past the midpoint. She doesn't make any decision about her fate, nor do her actions have any impact on the story.
- The cure was never a solution for humankind. The main problem of TLOU's world is that society is fucked up, regardless of infection. The infected had become "background noise." Nothing in the game suggests they are a major issue. Communities are fighting one another for resources, pretty much like in Mad Max. The fireflies are a paramilitary group that would never deliver the cure to any people other than themselves. That premise contradicts everything the game has shown you up to that moment.
Besides, the cure doesn't prevent the infected from attacking and murdering people. What would it solve exactly??? Yeah, you don't get infected if you survive their attack, but most likely, they would eat you alive. This is not like in WWZ. The game never tells how it would work because it is bullshit and Neil knows it.
Therefore, a hypothetical TLOU 3 with "the cure" as the main theme would be an awful decision. It would need a dozen plot holes to work, and even worse, it would deem Joel's death and other events of previous games unnecessary, and there is no worst mistake you can make in a saga than cancelling what has already been established.