A victim of an allegedly unprovoked one-punch attack in Ipswich, west of Brisbane, is on life support and may not survive, a court has heard.

The 56-year-old Lindsay Ede was allegedly punched in the face by 19-year-old Ariik Mayot in Goodna yesterday afternoon when they crossed paths in the street.

He fell and struck his head on the road.

Mayot faced the Ipswich Magistrates Court on Tuesday, charged with grievous bodily harm, drug and stealing charges.

His bail application was adjourned after the prosecution told the court the charge may be upgraded to unlawful striking causing death if Mr Ede did not survive.

The charge has a mandatory life imprisonment.

Mr Ede is in an induced coma in the Princess Alexandra Hospital and his brain activity is dead, the court was told.

He is expected to be taken off life support and is not expected to survive, the court heard.

Evidence presented to the court heard that Mayot callously and calmly walked away while Mr Ede was on the ground.

A police prosecutor described the teen as having a "disturbing propensity for violence".

"[It is] an appalling act of random and unprovoked violence, virtually a king hit," the prosecution told the court.

Prosecutors objected to the bail application, saying Mayot was an unacceptable risk of reoffending and endangering the safety and welfare of the public.

He was remanded in custody, with the matter adjourned until June 30.