Saw an interesting article in IGN regarding the Sony PS3 and PS4 digital games DRM. If your console's internal battery is dead and Sony has stopped their services you cannot play the games you bought any longer.
in.ign.com
It seems to be even worse on PS4, you cannot even play physical games:
Probably stops me buying another Sony console in the future. I wonder is the situation same in PS5 and/or in Xbox, Switch world?

PS3 DRM Kills Digital Games: Report
If Sony’s servers go down so does your digital library. PS4 owners have it worse though.
It seems that if your PS3 is unable to connect to Sony’s servers or that if the battery powering its internal clock is dead (also known as CMOS battery) or has low charge, you won’t be able to access any of your digital PS3 games. This includes PS1 classics as well as PS3 digital downloads. At best, some digital purchases may revert to trials which was a little used feature that allowed you to play a game for up to an hour and save your progress and trophy over to a purchase of the aforementioned game.
It seems to be even worse on PS4, you cannot even play physical games:
PS4 owners have it worse as IGN India reported earlier this week. If Sony decides to take down its servers, you also lose access to your physical game library. According to trusted hacker Lance McDonald this is because trophies on the PS4 need the console’s internal clock to work correctly so as to prevent users to change date and time values and exploit the PS4’s trophy system.
Probably stops me buying another Sony console in the future. I wonder is the situation same in PS5 and/or in Xbox, Switch world?