Does visiting a patient who is unconscious and knows no one cease to be a duty? And are there any Shar'i proofs for that?

Visiting a sick Muslim is their right, and it is an act of worship with immense rewards. Its purpose is to comfort them, reassure their family, and pray for them. Scholars have not differentiated between the permissibility of visiting a sick person who is sane and one who is not. The default is for the texts to remain in their general application.