Well tricky question. Because rather than timly alignment,
I believe that the hardware, software and feature set of a system defines with whom it would have to be grouped together.
Some people say nintendo started 9th gen early with the switch. However, that means that if the same people consider PS5/XSX 9th gen aswell, you can have a set of systems launch early, and another set of systems launch (way) later, and still consider them the same gen.
Using that argument + what I said first means that the WiiU is technically the same gen as PS360, which would make its successor the same as Ps4/Xb1 (8th)
However that would raise the question, where the Wii belongs to.
Assuming the Switch even belongs into the HC generations, it would have to be a late inclusion in the 8th generation, therefore PS5/XSX being the only 9th gen systems and the answer to the topics question being: no, PS4 didnt manage 50% market share, and so wont PS5 once Nintendos "9th gen" system is out.
Nintendo Switch:
... announced as a Home Console
... advertised as a Hybrid
... delivered as a Portable
