Since Vatican II, Catholics have taken great pains to speak of Protestants and the Orthodox as our separated brethren, whereas before we called them heretics and schismatics. It's been mostly a one sided love affair, but ecumenism is a huge industry within the Church so it's not going away any time soon, alas. However, when it came to the SSPX, even the most liberal Catholic ecumaniacs became the second coming of Pope Innocent III, hurling thunderous anathemas and interdictions from on high and loudly demanding that the SSPX submit to the pope's authority and repent in sack cloth and ashes. Would that they were so eager for obedience to the papacy in other matters.
It's obvious by now that Pope Francis is a liberal who doesn't care to get into the finer points of doctrine. Time and again, conservative Catholics have wound up with egg on their faces when they denounced a liturgical abuse - such as washing women's feet on Maundy Thursday - only for Pope Francis to do it himself. Ironically, because he doesn't care all that much about doctrine or canon law, Pope Francis has pretty much brought the SSPX back into the Church's good graces. It will be difficult, if not impossible, to revoke their faculties once the Year of Mercy is over barring any major transgressions by the SSPX.
Whether he did this with full knowledge beforehand or unwittingly, Pope Francis has done a good thing here. Here's hoping the SSPX is fully integrated into the mainstream Church; she desperately needs a homeopathic injection of that old time Tradition.