Doesn't seem plausible to me that Apple will release a "M3 variant" that can drive "tandem OLED" displays. So probably logical to package whatever chip progress (including process improvements) into "M4".

And it can signal that "We are serious about iPad as a computer", using their latest chip.

Logical alignment to progresses in engineering (and manufacturing) packaged smartly to generate marketing capital for sales and brand value creation.

Wonder how the newer Macs will use these "tandem OLED" capabilities of the M4.