So far it looks like this - a next gen engine is one that supports real-time global illumination, significantly increased particle count and features of the dx11 api at a min of 30fps @1080p, allowing for upscaling. If a console can do that its next gen otherwise its 7th gen.
At this point all you're doing is arbitrarily defining terms to fit which consoles you want to include and not those you don't.
In any case, this isn't a definition of the term "next gen." This is a definition of the term "eighth gen," and a shaky one at that. The debate here is whether or not you can provide a solid definition for what clasisfies any given console as a certain generation of console outside of it simply being the next one.
If you can, then present it. If not, then this debate is pretty much over (as it has been for the last page or so).
