Actually fire fighting planes tend to be extremely durable and last for a very long time. There are water bombers from the 1940s which are still in service today, 70+ years later.
As far as I know Bombardier had zero CL-415 pending orders before closing the factory. Zero! That gives an idea about the size of the market.
Plus there are alternatives from China, Japan, Russia, even from the US, for both amphibious and non-amphibious fire fighting planes of various sizes.