The coolant escaping into the passenger compartment could contact the driver's feet and injure the driver. Also, steam from the heater liquid will cloud on the window surfaces and impair the driver's vision. In either case, failure of the heater core end cap could result in a vehicle accident.
Visibility — Defroster/Defogger/Hvac System — Heater Core
The end cap connecting the heat exchanger's core to the engine cooling system could rupture and allow hot coolant to escape into the passenger compartment.
