1. Wrong premise and wrong conclusion. What is true firstly is that there is no strict heresy in Vatican II's ecclesiology and that, therefore, the errors in the Church today coming from it can and should be resisted from within, that is, with canonical standing in the Church, like the SSPX now has.
With regard to EENS, in the first place, the dogma states this - heretics, schismatics and infidels who finish this life obstinate and unrepentant in the mortal sin of heresy, schism and infidelity respectively die outside the Church and are lost. It states this much and this much only. It doesn't state - no matter how much Dimond/Feeneyites and other rigorists wish it - that those also, for instance, in material heresy or schism are also schismatics and heretics properly and formally so called. Sacred theology, going back to St. Thomas, also distinguishes positive (which is self-willed and mortally sinful) and negative infidelity (which is not) just like material and formal heresy.
2. Now, with regard to those excused by invincible ignorance from the sin of heresy or schism, we must consider first separated Christians who believe in Christ and the Triune God. If they are excused from sin by an ignorance which is inculpable, they are not formal heretics or schismatics, and consequently can belong to the soul of the Church by implicit desire, if they believe in and love God One and Triune with all their heart, and strive sincerely to do His will as best they can, Pope St. Pius X and several others bearing witness. Thus, they can be incorporated in the Church.
Secondly, with regard to non-Christians, the doctrine that there is no salvation without the Catholic Faith (which requires, at a minimum, explicit faith in the Trinity and the Incarnation), together with the fact that "God wills all men to be saved and come to the knowledge of the Truth" means that He will provide for the sincere non-Chrstian who seeks the truth with his whole heart the means to come to the knowledge of Christ and be saved. Fr. Mueller, in a catechism approved by Rome, expressly teaches this.
3. None of this denies the literal sense of the dogma, which is that all who die as heretics, schismatics and infidels properly and formally so called are lost. The dogma is speaking about formal heretics and not about so called "material schismatics" who are not really schismatics at all since the will, and therefore the sin, of schism is not really present with regard to its interior effects. And so, likewise, for heresy and infidelity.
I like how the most stubborn Feeneyite/Dimondite posters here nonentheless say, "If I am wrong (about the Pope/modern crisis etc), I hope God judges me to be sincere and inculpable, because I sincerely love Him and desire to do His will" while denying precisely the same to those far less guilty than they. An Orthodox Christian, born in a separated Church, but nonetheless desiring to serve the Triune God and belong to His true Church with all his heart, is within the Church by virtue of that very desire. In a similar state exactly, are sedevacantists, Feeneyite/Dimondites and other modern heretics/schismatics/dissenters, if, known to God, they err in good faith and are not obstinate in their error. But since God judges every man by his own standard, as St. James admonishes, and if you insist that every person in heresy or schism is a formal heretic or formal schismatic, then you yourselves risk being judged by God as exactly that, as formal heretics and schismatics yourself.