On reading the Daily Mail report that the submarine is only in 230ft (well within the range of competent divers) I became more optimistic that a rescue could be effected, because there would not need to be a long delay getting the USN's specialist ROVs in situ, and because rescue could be effected by divers even if the submarine is lying on it's side.
La Nación is reporting now that of the 44 on board, 6 are "Buzeos tacticos" who are the Argentine equivalent of SBS and who are all highly trained divers, and would be trained in underwater egress from a submarine. I would have thought there would be an escape attempt by them by now, if oxygen levels were critically low, and if the boat really is in 230ft. So maybe oxygen is not yet critical, or else the scenario is bad.
The Argentine Navy are also reporting that the oxygen situation is only an estimate, and that they could have sufficient for ten days (ie another 3). Also, the original electrical fault was caused by a water ingress while operating at snorkel depth.
El problema eléctrico se originó a raíz de una entrada de agua - 22.11.2017 - LA NACION