That aside, any company that relies on software for the proper operation of their product - which basically covers almost all technology and consumer electronics manufacturers, would have to be very dumb to just count on the continuity of employment of their software developers to sustain a successful business model.
I'm not exactly sure what you are getting at. I don't mean that you have to be prepared for developers to leave. I mean that from a product development lifecycle, there isn't really enough work to keep developers in all areas fully employed, so as a result anyone who isn't Harman sized has to hire consultants. A change will require a new project.
So, either you are in constant product development, justifying developers or you are on a project by project basis, and have serious fees incurred each time.
Unlike, say, an amplifier, which you pay to design once, and then you pretty much run it for 10 years if you can, or 20.