They are dragging this too much. We get it, humanity is cooked, Carol is lonely AF to go along with being miserable (a character trait), and Manu from south america is a hardcore MF. We also know what's going to happen in S1:
Manu will go thru trials and tribulations and eventually link up with Carol (OMG a human connection with someone who has the same core belief like I do that this is all wrong!)
They'll set off on their cure journey
S1 will end here somewhere, S2...
Multiple advances and setbacks on the cure journey
Eventually they figure out how to turn a single person back, probably an actual scientist
The hive shows signs of getting more adversarial
S2 ends around here, S3...
The hive converts Manu, who we now love, Carol has to do a thing to bring him back
Reveal of the ticking time bomb for the series end in S4: e.g. the mothership is coming, or the food sitatution is so critical 99% of humans will die in 6 months, it doesnt' matter what it is they will just need something
Hive and Carol's team realize they have area of cooperation and reluctantly work together on a thing while simultaneously and secretly working thier own plans
Ominous closing shot of the whatever the ticking clock is counting ever downward
S3 ends around here, S4...
Final sprint to the mass cure
Surprise: Hive finally figures out how to easily convert Carol!
They give her a choice and it's F-no
They decide that their imperative overrides that choice and give her one more week to enjoy autonomy before conversion
Carol and her ragtag team finally crack the code on a COVID-like airspread virus to reverse the hive and set it to go off...
...but Carol's time runs out and she gets converted! Too bad the clock is already ticking on her team's cure virus release
Cure virus hits, people start to get converted back, chaos ensues (OMG humanity is so bad and life was so better before!), The Others have their "I told you so moment," more people die but the cure is spreading
The script flips and now it's the Hive that's going into hiding to prevent their conversion back
Series ends with the final pocket of the Hive sealed up in a bio-research facility where they can filter the air. Carol talks to her homegirl across the glass and the Hive pleads for mercy/we were just trying to do the right thing/let us make our own choice, whatever.
Series ends on Carol's hand hovering over the button to push the cure virus into lab with the final group of Hive ...does she push it and eradicate their species? Or not? Oh, so mysterious! Fans of the show in outrage over inconclusive ending and demand S5.