With matters relating to divina natura, you are getting a bit into the realm of philosophy, and quite honestly I think that very few authorities in the Church today would take the question that far. I have no problem with asking it, but I think you can rest easy knowing that very few priests, short of a few astute canon lawyers and STL/STD's will ever get into it outside of an academic setting.
Obedience is another issue that has to be specified. Are you speaking of the general rights of the faithful under say canons 220-230 and how their speech and actions relate to the Church, pastors, etc., or are you speaking of vowed obedience, such as that of a cleric, postulant, novice, etc. The former is not as defined as the latter, e.g. laity cannot be commanded in the same sense as a religious or someone under the vow of obedience.
Thus if you're asking whether a "traditional Catholic" layman can still be that if he disobey's some type of order, I would ask what you mean by order because no cleric, even a Pope, can technically order a layman to do anything short of things like form of penance and related sacramental matters like don't eat food one hour before receiving Eucharist, things like that.
If some yahoo sedevecantist is running around saying the Pope is not the Pope, that person is already ipso facto in a state of latae setentiae, automatic excommunication from the Church and cannot receive any of the Sacraments until a full confession, penance, and prayer. Hence, such a person is in schism, so there I would say that person is not Catholic, not anymore.
Note: do not attempt to draw comparisons to Mass where the priest there is giving a sermon
On your original question of obedience, one should ask themselves why are they choosing to be disobedient. The vast majority of the time, the disobedience is ordered towards the devil and sin. Another question is what is how far the person is going in decrying something as immoral. Luther went to the extent of deciding that some of the fundamental doctrines of the the Catholic Faith were wrong and so rejected the Church as a whole. German princes jumped on the bandwagon as they wanted to rebel against the Church.
The lack of canonizing Savonarola can be explained by three possiblities:
- He went too far and is in hell
- He is in purgatory.
- God does not want an example of a rebel (for any reason) being canonized lest people who rebel for objectively sinful reasons twist and distort the saint beyond reason to support themselves.