Procedural
An engine fire and shut down would require the aircraft immediately divert to the nearest suitable alternate.
For and A320 say, subject to winds, a rough rule of thumb for a 260Kt descent, is to take the altitude of the aircraft in feet, divide by 1000 and multiply by 3 to give roughly the distance to land in Nm.
e.g. 25,000 feet x 3/1000 = 75 Nm or roughly 15 mins
For a 120 min ETOPS this means the second engine must keep the aircraft at 25,000 feet for another 105 mins (bleed reduction)
Depending on when the second engine failure occurs, a non suitable landing field or ditching might be contemplated.
With no suitable place to land in sight, one might be tempted to weigh up the risks of restarting on the basis the fire warning that lead to the shutdown was false.
Of course, a fire can destroy the aircraft and its occupants if it cannot be contained.