It is not just four Cardinals, you know that as well as I. There is a massive schism over this exhortation, look at the difference between Archbishop Chaput's interpretation and that of Cardinal Cupich and bishop McElroy.
Cardinal Müller has persistently come out in favour of the four Cardinals until today when he stood upon the fence. He has consistently said up to now that the divorced and remarried cannot receive Holy Communion whilst committing adultery. Is his position as prefect of the CDF now under such threat that he has to acquiesce or resign? It seems that he has chosen to acquiesce. Despite this I can't see him existing as Prefect for very much longer. Pope Francis has emasculated his dicastery, more than likely he will fill it with his cronies and leave the unfortunate Müller a king without a kingdom. This seems to be his modus operandi since sacking those with whom he disagrees has not worked. Sack all those who agree with the head of the dicastery.