If the antidote could be used now, after the toxins were cleared and with recuperation, Nathan could fully recover. However, he would still be weakened and he wouldn't be able to live long.
For now, Nathan had a few options.
He could sit and wait for death. Perhaps in a few years, his internal organs would completely shut down and he would die painfully.
The other option was to ask Damian or Anthony to donate their organs and he would change all of them. Nathan would live a few more years, but Damian and Anthony might die.
The third option was to wait for the research team at Jordan Medical...