This may not be rocket science, but as a former engineer for NASA and McDonnell Douglas, I can vouch that navigating through AL and the theological nuances seems much more difficult.
Ir I am an engineer also and while not a rocket scientist I regularly play Chinese chess with a a retired high level rocket scientist from China…and I win at least as many games as he

.
But other than to demonstrate we are both capable of appreciating logic, seeking objective truth and dispassionatley recognising the limitations of our data, methods and conclusions I don’t know why such is particularly useful in understanding the difficulties you are having.
I do not deny the speculative possibility of the position you ate taking…though some here appear to deny even the speculative possibility of the one I and others take.
At a prudential level I find your position no stronger than that of the geocentrics…sure if you do enough mathematical backward flips it can be made to work. I shave with Ochkams razor myself in a world where there can only be models of reality as opposed to absolute truth.
Magisterial teaching and our appreciation of it in many areas is art as much as science.
For myself I am quite confident in the art of situating modern Magisterial statements within the very different camps of tradition, dogmatic theology, ancient pastoral praxis, Liturgy, Canon Law etc because I also have 6 years of Dominican theological education in theology/history under my belt. Autodidacts are always at sixes and sevens in these sorts of jelly like discussions I find.
Now considering that a statement is not infallible by virtue of its presence in an apostolic exhortation, but rather, a statement on a certain teaching can be considered infallible if it has been taught consistently, constantly and universally, having been taught through the Ordinary Magisterium, which is the more common and typical manner that the Church teaches doctrine
This is so vague a truism as to be meaningless in this particular discussion and is even circular. I think you will find it very difficult to establish this truism holds for the point we are actually putting in the spotlight, namely
“This norm … expresses an objective situation that of itself renders impossible the reception of holy communion.”
This is a wise opinion of Card Ratzinger that is Papally tolerated in a CDF publication.
When you can demonstrate it has at least the Papal or Conciliar provenance, tradition and universality of a teaching like that on Limbo or the death of Mary then it deserves to be taken more seriously.
But even these serious teachings are not infallible…which just goes to show how much more reasonable my position on AL and FC is compared to yours.
With that said, scenario number 1 presented above is a real possibility.
Yes, it’s possible the Pope is material heretic…and the longer he goes on stubbornly leading us this way the closer he becomes to being a formal heretic.
Realistic? …unlikely given his continuing de facto Papal support amongst leading bishops and Cardinals.
A minority disagree with him which is fine in prudential judgements. If the minority are opposed not simply on prudential grounds but on inherent theological grounds…I suggest their very small numbers and lack of both universality and Magisterial status suggest they have interpreted both tradition and history and Scripture wrongly. Admittedly a long standing Communion rule can take on the appearance of being an unchangeable theological teaching.
But if the Pope prudentially judges otherwise…there actually is no past teaching to deny his position. This question may just never have been addressed before.