no he never becomes protagonist again……….
And I did some reading Sasuke becoming an antagonist is actually chapter 181 so 75% of the series Sasuke is an antagonist/villain. Yes they fight together in the end war but everybody had to fight together otherwise the world is over. And let’s not act like Blackbeard and Luffy teaming up against IMU is out of the realm of possibility. They will both have beef with IMU for their own reasons. Antagonist can have good qualities to them , look at Katakuri.
And I did some reading Sasuke becoming an antagonist is actually chapter 181 so 75% of the series Sasuke is an antagonist/villain. Yes they fight together in the end war but everybody had to fight together otherwise the world is over. And let’s not act like Blackbeard and Luffy teaming up against IMU is out of the realm of possibility. They will both have beef with IMU for their own reasons. Antagonist can have good qualities to them , look at Katakuri.
Sasuke was never a protagonist (aside from a very short time where the story focused on him after the timeskip), Danzo was his Antagonist at this moment.
Sasuke is mainly an impact character.
And while you are right, it's not an impossibility for BlackBeard and Luffy to team up (which I doubt tho), the comparizon ends there. Blackbeard is and will always be an antagonist, you could even say, the main one.