In the end, Nathan successfully entered the cryogenic sleep that would sustain his life. The situation of his health would remain the same until they could find a way to cure him. Once they did so, he would be woken up from his sleep for him to start the treatment.
However, the future held too many uncertainties, the technology for cryogenic sleep was still in its infancy stage. Even though the field had been researched by a few groups decades ago, the majority had failed.
So far, only Jeremi was the successful case, though he only entered cryogenic sleep for a short period of time.
If the cryogenic sleep failed...