Back in April, it was discovered that the combination of closed servers and dead clock batteries for PlayStation 3, 4 and in some cases 5 ultimately led to games not being playable, not even from discs or offline, or even if you switched the battery.
As Sony has started to shut down a lot of older systems, there was an outcry from gamers worried that all their older games might be rendered useless. But fortunately, the attention to the issue from gamers and media seems to have led to a solution from Sony with the 9.0 PS4 firmware update. The Twitter user Destruction Games has tried it out and everything works even as the battery is dead with no servers, as has other people with the same positive result.
So far this only applies to PlayStation 4, but hopefully it will be implemented for PlayStation 3 as well. Sony hasn't said anything about this officially yet, but the results seems to speak for themselves.
Thanks Neogaf