There’s no hard and fast rule that says how old a console needs to be for it and it’s games to be considered retro.
There are a lot of people that say that anything from two generations ago is retro. That would put the PlayStation 3, Xbox 360 and the Wii in the retro camp.
Do you think the PS3 generation is retro or if not what consoles do you consider to be retro systems?
For it to be "retro" a paradigm shift has to occur. Considering that PS3 and 360 were both HDMI systems, with online play, friend lists, private messaging, bluetooth/wireless headset supporting, and both have achievements, tell me, is that very different than the systems that are currently available? All that's really changing with your gaming experience is playing games with worse lighting and the tedious mechanics that plagued a lot of gen 7 games. PS2 and og Xbox are definitely retro, but unless cloud gaming all of a sudden became the norm and consoles just became streaming boxes, I think PS3 and 360 are still modern consoles.