> On the other hand, there is proprietary software still running whose company has been gone for decades.
True, I'm sure!
Equally true of free software... and indeed when that situation does happen, you're in rather better shape if it's free software than proprietary.
I think there are good reasons for people to keep their software installations generally up to date, though -- certainly anything that's exposed to today's Internet. And for a given version of $component, the OS versions that shipped it will only continue getting updates for so many years. Because of that, in the example I was replying to I don't think it's unreasonable to see an announcement that, strictly, just says "this feature will be dropped from future versions of this software", and think of it for practical purposes as "this feature will be going away".