Dunno if this is exactly the kind of thing you have in mind, but a person known as 'Yuvi' has been singlehandedly maintaining publicly available servers for the original Demon's Souls for about 4 years (the official servers shut down about 5 years ago).
Thanks to Yuvi, you can still play the original game with all online functionality, regardless of whether you're playing on PS3 or RPCS3.