I, nor anyone else, can say what God will do in such "hard cases" as you mentioned in the last paragraph. It is not for us to decide.
It is important that we understand that scripture must be looked at as a whole, and not just verses here and there. There are verses that teach belief or faith leads to salvation. There are verses that teach that repentance leads to salvation. There are verses that teach that confession leads to salvation. There are also verses that teach that baptism leads to salvation.
I ask you one question: Do these verses contradict one another, or do they as a whole, teach all that is needed to accept God's gift of salvation?
No, of course not. But it seems clear that while nothing can be accomplished without faith, the other items on the list have no meaning in and of themselves if faith is lacking.
Now, how faith comes about in the first place is another thread!
As you can tell from my tagline, I am a retired army chaplain. What is offered as a hypothetical is discussed among military chaplains as a reality. Battlefield chaplains have with wartime regularity been confronted with exactly this situation. For baptists it pushes their understanding of baptism by immersion; for Church of Christ (and others) it pushes their understanding of baptismal regeneration. Baptists will tell of baptizing with a canteen, and others will tell of no baptism at all because the situation and enemy fire is simply too great. Sacramental Christians will agonize over troops doomed within a contaminated area, because they cannot be present to administer that sacrament without consigning themselves to death.
Across the spectrum of chaplains, I never ran across one from any denominational group that believed God would be anything except understanding of those confronted by in extremis circumstances.