Think about like that - if it is hater matrix, it may just end in one moment - u will get car full of steam and u will be forced to use trailer - because there will be no coolant in cooling system. Or, if it's water pump, which is leaking, there will be something similar.
U can just check - get little piece of steal pipe, with diameter suitable for heater's hoses, and disconnect hoses from matrix and connect them together, using piece of pipe and clamps
Then u will see, there will be coolant leak or not. I did that year ago, when I drived for some days without dashboard and heater
