When something similar happened in the UK, it was pretty much exclusively smaller/niche forums, run by volunteers and donations, that went offline.
[Warning, IANAL] I am really not sure if the experience is transposable for two reasons:
- UK follows Saxon tribal law, while Brazil follows Roman civil law. I am not sure but I believe the former requires both sides to dig up precedents, and that puts a heavier burden on the smaller side of a legal litigation. While in the later, if you show "ackshyually in that older case the defendant was deemed guilty", all the judge will say is "so? What is written is what matters; if the defendant violated the law or not.".
- The Americas in general are notorious for sloppy law enforcement. Specially Brazil. Doubly so when both parties are random nobodies.
So there's still a huge room for smaller forums to survive, or even thrive. It all depends on how the STF enforces it. For example it might take into account that a team of volunteers has less liability because their ability to remove random junk from the internet is lower than some megacorpo from the middle of nowhere.
Additionally, it might be possible the legislative screeches at the judiciary, and releases some additional law that does practically the same as that article 19, except it doesn't leave room for the judiciary to claim it's unconstitutional. Because, like, as I said the judiciary is a bit too powerful, but the other powers still can fight back, specially the legislative.
Memory is a funny thing. People around me often highlight that I remember oddly specific stuff, but I forget what they make a huge deal of.
So for example, I do remember the name of the girl of my first kiss. And her face, including her ears. Her birthday too, although that's because it's close to mine.
I also remember the weird smell of the nurse who took care of my sister when sis was internalised, 30 years ago. (I was 9 back then; now I know the smell is disinfectant). I also remember the specific pitch of my neighbour's dog "yuuuunnn~", as he brought what-used-to-be-a-ball through the outer fence of his home, so I could throw to him. (I had dogs back then, but neither was into playing as much as that good boy.)
I also remember my grandpa completely drunk, but taking care of me, when I was 6. And my grandma scolding him for that. Or the toy grandma gave me, a coin that flipped as if it was "magic", as it went through a house-like thing. (It was themed after Ducktales.)
However I'd be lying if I said I remember the face of my father, even if I lived with him until he died (I was 18). I also tend to forget the specific date of my nephew's birthday, even if I care a lot about him. I'm also always pausing to remember how many tablespoons of coffee I need to add to the machine, for a specific amount of coffee.