I see as retro as everything that's unsupported (doesn't get new official games, hardware isn't sold) and emulateable.

I mean, yes sure SNES feels "more retro" than a PS3 for sure, but games in 8bit or bit style are still made today. And after the sprite-based consoles, there is no clear cut anymore.

I suppose you could make a cut at shader support, i.e. after PS2, but then then the OG Xbox is between worlds then and spoils the generational difference.

Someone suggested HDMI, but the first iteration of X360 didn't have that, while older consoles like GC can be more easily retrofitted.

So, either the cut-off is between sprites/16b and 3D/32b, orrr... Just the support.