Generations are defined by time, not by power. If your father is strong and your are a weakling you are still one generation "ahead" of him. If the PS5 has half the power of the PS4 Pro and is a hybrid system it will still be a next generation system.
So, if we really want to keep things in order: Going strictly by timing of release (!) and ignoring all that "power" talk I'd say PS4 Pro, Switch and Scorpio are generation 9 consoles. I know some people's ego depletes if their console isn't a generation ahead of everyone else's (or whatever the matter is here) and I know PS4 Pro and Scorpio are just beefed up versions of their original incarnations - but so what? Who cares? All we need generations for are Wikipedia articles and that would be the neatest way to sum everything up. No console has to feel singled out this way, isn't that great?