Yeah, I've been around since this was a BTS-related game, and while that is what intrigued me, I stayed because I loved the story (and I'm a major sucker for cyberpunk XD).
To answer your question, the main story line essentially. Pretending everything went according to plan, the complete story line you had set up for TTEOTS. So the Prologues and chapters fit that, while, in my opinion, the POV (like Four's) are extras and outside of the OG. Whatever was slated to be the tale of the original novel including the little premium conversations, should stay within what was originally charged, if it was premium. I like to think of it in the video game sense. Technically speaking TTEOTS can be played without knowing Four's POV, it is completely unnecessary to the original novel as it is not an essential plot point. Four's POV however, is a wonderful expansion on what happened, and how Four behaves AKA his character. Therefore, Four's POV, in my opinion is the DLC to the TTEOTS game (literally and figuratively lol). I didn't mind paying extra for it because it was outside TTEOTS but I think future fundamental plot points shouldn't be behind a paywall. Ah, I hope I explained it well. I am terrible at articulating my thoughts more often than not so I hope I got my thoughts across.