I post this because there are a few people on this forum who are still on the Fermi cards. In addition, those here still on Kepler should be on watch as they are the next generation up.
In short, no more features and bugfixes, no support for new API’s, even the critical security updates will vanish next year. Anyone still on the 580 for instance will have to upgrade (which I would argue could be a little bit of a bum deal right now with the prices).
This also means the death of 32 bit for Nvidia owners (regardless of the generation owned). This though can be seen as a good thing, as it will allow the Blender developers to remove all 32bit specific code and drop the maintenance needed to allow such builds to compile. Still, that generation was well known for its performance and prowess as rendering machines (noting the early Cycles demos).
I guess it was to be expected eventually.