At every company I have been at with some history (more than a decade or two), I have found there to be at least one product that is long beyond the “Milk it” stage. Orders have dropped off, and customers have moved to either a different technology, or into a replacement product. Of course, you still get the occasional batch of orders for it, thus the hesitancy to discontinue it formally.
The development of a product should follow a lifecycle from investigation, definition, to alpha, then beta and production. You will note that I didn’t say “and finally, production”, that is because there is one more phase that is difficult to actually achieve, obsolescence or discontinuance.