In our currently troubled economy, there is more risk than ever that companies will go under. Those that don't are probably considering trimming the fat on their product portfolios and concentrating on their biggest money makers.
This presents the possibility that some software products may be discontinued or abandoned. My plea is this—that companies open–source their software under an approved license if they are no longer marketing it.
While open–source is not a panacea for every application out there, it does at least add to the wealth of code available to programmers. Why reinvent the wheel if there is already a servicable component to use? Some software is reinvigorated via the open–source model. Some may just benefit other programming projects.
Of course, there is the possibility that a vibrant community will develop around it and opportunities may arise for providing support contracts. An example of this might be NetManage ECCO Pro (though not open–source). Another scenario is that programmers who worked on the product might continue to do so in their spare time, perhaps even with encouragement from their company. This demonstrates good will and is appreciated by many developers and end users. An example here might be OpenOffice (if there is a better example, please post it in the comments). Really, I am surprised that more companies don't do this.
I think perhaps some of them are afraid that the open–source product might be competition for them. Lay your fears to rest. If the open–source revolution has demonstrated anything, it is that despite there being high-quality, free solutions available, most companies continue to purchase commercial software.
Perhaps they do so partly out of habit, but more often than not, they do so because they have a company to hold accountable and service contracts to help with bugs or other issues they encounter. In fact, it is rare indeed to find a company that relies exclusively on free software.
As for competition—I think most people agree that a little competition brings out the best in all parties. It could be argued that many commercial products owe at least some of their success to competing with eachother and with free solutions. Competition drives innovation.
Once again, please consider releasing code for products that are no longer in your portfolio, or to your software assets if you are unfortunately forced to close your doors.