When you are a) absolutely convinced of the righteousness of your position and b) not at all exercised about the need to be in union with the Pope, it must be hard to see any reason for a reconcilation. Indeed, the big surprise would be if a reconciliation were to take place.
The FSSP split has already taken away those who see union with Rome as an important issue and as a result, those remaining are probably never going to be too anxious to heal the rift.
Maybe Fellay wants to see who the next Pope will be. He might be pleasantly surprised. Then again, he might not. He may not even live to see the next Pope. Who knows what tomorrow will bring? The longer this drags on, the harder reconciliation becomes in my opinion.
Who says the SSPX or those who attend their Masses are "not in communion with the Pope"? This is patently absurd, especially since the Society and its followers pray for the Pope daily and reject any notion of sedevacantism. Claiming they are not in communion is based on a unilateral presupposition that the only motive Archbishop Lefebvre had for consecrating bishops without a papal mandate was to deny the Pope's authority. This is nonsense. The motive was to protect the ancient Mass from extinction and to save souls from perdition. This was wholly lawful and good--regardless of the spin placed on such an action by the Pope himself.
The FSSP has already split? I'm not surprised.