Coolant tank off a 09 dodge nitro 3.7 - 2009 Dodge Nitro

SOURCE: Dodge nitro leaking coolant slowly. Wil it last much longer

A lot depends on where the leak originated. If it's the water pump, it will only get worse, circulation will be impaired, engine can easily overheat...won't ;last long.
If it's an external leak, and you don't let the coolant get too low, it can go a l;ong time, with daily or regular topping up of the radiator.
If it's a blown head gasket and leaking internally, its days are definitely numbered. If its a head gasket and leaking externally, a little safer, but iffy: the head gasket may keep eroding and the leak get bigger. Overheating of the engine may occur.