would it also apply to stuff like the Switch, and relatively high-end "mobile" gaming in general? (I'm not sure what those chips actually look like tho)
there are also some arm laptops that just run Qualcomm chips, the same as some phones (tablets with a keyboard, basically, but a bit more "PC"-like due to running Windows).
AFAICT the fusion seems likely to be an accurate prediction.
Switch has its own API. The GPU also doesn't have limitations you'd associate with "mobile". In terms of architecture, it's a full desktop GPU with desktop-class features.