Were the Pope to accept the sspx back en masse and permit them to continue to repudiate the Second Vatican Council and consider it heretical; if the Pope let them continue to repudiate Canon Law; if the Pope let then continue repudiating the Catechism; if the Pope let them continue to teach the Normative Mass is evil; if the Pope declared all their celebrations of all the Sacraments are now licit; if the Pope granted them any structure they desired, there is one thing he can not do.
Even if he made concessions in all the areas I noted, the reconciliation would not occur if the Pope demanded they repudiate their heretical antisemitic doctrine the Jews are cursed.
Were it learned the SSPX had entered into negotiations with the Holy See and part of the negotiations included the Pope's demand the cult repudiate their antisemitic doctrine the Jews are Cursed while conceeding ALL their other demands, their followers would be screaming "Fellay is a Judaiser" and there would be no reconciliation.
It is NOT the Mass that matters. That is a mask. Their base is bound together with their base and hateful doctrine the Jews are Cursed. And that is a doctrine they will negotiate.
and that is not a doctrine they will negotiate