Here's a fun question - when does a video game, or video game system, become retro? Is the system simply being discontinued/obsolete/replaced by a number of console generations enough, or does it require a long period of time...and if so, how long? Ten years? Twenty? Would you consider the sixth generation of consoles (or even the fifth) retro now that we're approaching the end of the eighth generation, or has technology not advanced sufficiently/not enough time for passed to consider these generations and their games to be retro?
I feel like this is hard to quantify, since what anybody considers retro it pretty dependent on how old they are. Personally, I think that once things are out of production and it's been 15-20 years since their release, it's fair to consider a game system and anything that would be played on it "retro".
... I think the best way to classify a console as Retro is when the manufacture no longer supports the console in everything.
If you got a busted Nintendo 64, you can call the repair line and they'll support you on repairs, however in terms of sending it in to get it fixed, parts and what not; you're better off ordering them from a 3rd party and fixing it yourself.
By-the-by, what do we call SNES, NES and So on when the PS3 and PS4 Goes 'Retro?' Ancient?... I'm joking of course since they already are, though the WiiU, PS3 and Xbox 360 and up still have proper support since they are the most recent since their production lines have halted. When the next generation comes in, those will no longer be supported and it'll be the PS4 and Xbox One X.... Switch is coming up with a Switch PRO, so Nintendo isn't giving up on that baby until they go full VR.
... There's another problem; Gaming has reached it's peak in how we play and interact with it; unless we can simulate entire environments in our bedrooms, living rooms or anything else, there's no other direction for the consoles to go. They'll need to explore new ways to play video games and while Nintendo does that already, Microsoft is sticking with their guns as well as Sony; but they're going to faulter here until another group comes along.
Maybe a WonderSwan revive for the west or a PSP2 with proper L2 and R2 buttons... WHO KNOWS!
I would have to say there is a two console generation gap between what is currently on the market, and what is considered retro. Right now I would say the late PS2 era and before would be considered retro, When the next generation launches, the early PS3, X Box 360 games would be considered retro. Or that is just the feeling I have.
While I personally tend to think of "retro" as anything up to the generation of the first console I had (the PS1), I think a better and less personal way of defining that could be using mainstream game stores' used games section, and call "retro" everything that's no longer available there. So for example in my country GameStop does not sell any used PS2, GC, Xbox, and GBA games anymore and so I think that generation should be considered "retro", as you need to go to used goods stores to find those games or consoles.
I consider anything two console generations ago or earlier to be retro. At the moment, the newest consoles that fall into that category are the Dreamcast, Gamecube, PlayStation 2, and Xbox. By then production is mostly gone. Most major store chains no longer stock the systems and consumers are generally more interested in what's newer.