I think my post was unclear since you are not the first user interpreting it in this way. I'm not saying companies should port their software to new operating

I think my post was unclear since you are not the first user interpreting it in this way. I'm not saying companies should port their software to new operating systems and software stacks (presumably forever). The user would be responsible for providing whatever operating systems and software stack the program was built to work on. What I'm saying is that it that companies should provide some way for users to continue using the product they bought, on the same software stack they were already using, when the company decides to shut it down. Anything better than the current situation where the online servers just go down and nothing is offered as an alternative would be much better. One pretty good way (but not the only one) they could do this is by releasing their server-side software, as it is. They don't need to open source it, they don't need to port it, and the user would be responsible for providing whatever underlying software stack it was designed to work on.