According to Cardinal Mueller, the Church is already in de facto schism and has been since the ordination of the 4 Cardinals some decades ago. The SSPX has not been found in schism de jure; and having watched the matter for a long time, I suspect the driving force for the reconciliation has been along the lines that a de jure finding would make an already difficult situation nearly impossible.
As to what will happen, there comes a point where the SSPX will be faced with facing the possibility of ordaining more bishops. At that point it will be up to Rome as to how to proceed. Pope Francis is, if anything, a pastoral Pope, something that is reflected in his prior history of concern for the laity. He has made repeated comments about the need for all ordained to be among the sheep. How he would react is anyone’s guess, and that guess can go either direction; and if the matter does not come to a head, it will certainly depend on who is next elected Pope.
I certainly do not know the inner tensions within the SSPX. There has been a long history of “we are close to reconciling” for so long that it appears to be “different day, same tune”, and they have their own history of break-offs. Stories come up fairly regularly of SSPX chapels in different areas on a spectrum from some cooperation with the local diocese to isolation from them, so it is not as if the SSPX are a monolith all marching to the same drummer. Or perhaps, some seem to be more likely to reconcile; others seem to be unlikely to budge.
And while much has been said indicating to some that Pope Francis is far more open to reconciliation, others look at the matter and see him concerned far more about the laity who follow the SSPX than the members themselves, a way of saying that his move was not to move the bar with the SSPX themselves but rather to administer to the laity caught up in the matter.
To put it in the vernacular, I don’t have a dog in the fight. I simply watch; it has been 31 years since the ordination of the four bishops And for all of the discussions, we are in the same position.