The man, named in Blackpool Magistrates as 47-year-old Michael Rhodes, was today in Royal Preston Hospital after the incident on Saturday.
Prosecutor Martine Connah told the hearing: "It is unlikely that the aggrieved Mr Rhodes , will pull through.
"His injuries are life threatening and doctors are to switch off his life support machine today."
A 16-year-old boy is charged with causing grievous bodily harm and appeared in court this morning. The youth, who cannot be named but lives in central Blackpool, has been bailed until Thursday when he will appear before the resort's Youth Court.
It is alleged he landed a single punch to Mr Rhodes outside the Costcutters store on Exchange Street, Blackpool on Saturday.
The court heard the boy is likely to face a more serious charge if his alleged victim loses his life, the court heard.
The conditions of his bail means the youth cannot contact a list of 15 adult and youth witnesses.
He must live where directed by Blackpool Council.