I don't why you think that I believe there are no Catholics in hell. Catholics in mortal sin believe as the Church does. They can simply go to confession. Heretics are not in the Church and cannot go to confession without first reconciling with the Church and abjuring their heresy.
This is a lie in most instances as you must agree to there having been countless souls who've left the faith, apostatized, became heretics, murderers, etc., then returned without any abjuration at all. They simply went to confession, which is something only Catholics can - and the Church teaches - must do.
Your opinion above is most certainly not true if the heretic is in danger of death, and it's a flat out lie for those whom the Church has not officially imposed the censure upon, but even for those whom the censure was officially imposed:
Nevertheless, for fear lest any may perish on this account, it has always been very piously observed in the said Church of God, that there be no reservation at the point of death, and that therefore all priests may absolve all penitents whatsoever from every kind of sins and censures whatever: and as, save at that point of death, priests have no power in reserved cases, let this alone be their endeavour, to persuade penitents to repair to superior and lawful judges for the benefit of absolution.
Please tell me what it means to be subject to the Pope and where you get your opinion from.
It means that for our hope of salvation, we must be the pope's subject, but always God's first. Most (all?) sedevacantists leave the part out about being subject to God first, doing this serves only one purpose - as fuel for their "must blindly submit" ideas, but those ideas only work - and work well, only so long as they leave God out of the formula entirely.
So....being subject to the Pope means we must be the Pope's subject. Wow... that is...amazing.

Was not Christ subject to His parents?
"And he went down with them, and came to Nazareth, and was subject to them. And his mother kept all these words in her heart. Luke 2:51
Are not subordinates subject to their superiors? Children to their parents? - in all things except sin?
Do you understand what the word "subject" in this context even means? I'm serious, I've come to believe that sedevacantists do not understand what that word even means, they seem to think it means "submit", or "blindly submit", or "mindlessly submit" - is that what you think too?
Do you have any understanding at all of the Catholic principle of being subject to our superiors in all things except sin?