For example, I know in that article you mention bsnes, but wouldn't it be exponentially more difficult to have that feature in something like a GameCube or N64 emulator (let alone something like a PS3 with its funky Cell architecture)?
The more modern your game system gets, the harder it is to perform runahead. But it's also required less and less. Newer consoles got more 'laggy' by default, with OSes, USB/Bluetooth input processing, triple buffering and so on. So runahead requirements have become less and less to recreate experiences.
As to you examples, the PS3 was meant to be played on LCD TVs much like our current setups. I don't know how RPCS3 compares to a real console, but I expect the difference isn't huge. Dolphin (GameCube) and Mupen (N64) can emulate their consoles so efficiently that you should be able to achieve 1 frame of runahead on somewhat powerful systems for many games.