I find it difficult to believe... not because the intent, but the configuration.
Cortex X4 is meant to provide high single-threaded performance.
In multi-treaded sustained workload, appropriate to thermal and power restrictions, the X4 is expected to work not a peak capacity, and to more evenly distribute the power use between cores.
This leaves that proposed configuration as suboptimal. The "small-cores" A500-class can barely do a lift relevant to video games, mostly can see OS and I/O related task in background.
It makes more sense the 8-core A78 rumour, or either a 8-core A720 or 8-core X2/X3 but running at a lower clock speed.
I don't expect the Switch 2 to rely on a Quad-Core "Big Cluster" design, that's appropriate for a tablet, but not for a console design anymore.