Backwards compatibility is a huge thing with gamers. The capability of playing a lifetime of accumulated games after several generations of new hardware is one of those things that sell consoles. Sony’s PlayStation Vita is already capable of playing PlayStation 1 and PSP games; although needs to be bought via the PlayStation Network.
Eurogamer reports that while Sony is preparing to make PS3 games available to the current generation console via the new PlayStation Now streaming service, PS1 and PS2 titles will follow a more traditional emulator route. This would mean saving large amounts of bandwidth as compared to streaming the game off the PlayStation Now servers. It would also help those who lack access to reliable high speed broadband.
The PlayStation 3 also had backwards compatibility, although upscaling on the third generation console left many gamers disappointed with the results. It might be that Sony is planning to digitally remaster the old titles (again), which would allow classic titles to look like they fit on today’s HD displays. This situation isn’t too hard to imagine as the same was done with the PS3 versions.