Where such a 1980s-era microprocessor isn't excessive (asymmetric crypto, video/audio compression, etc), is relatively infrequent & often involves processing a lot of data. So I imagine something akin to an FPMA full of carry-save adders would be well-suited there!
I can see need for an NPU (I like Mythic's designs!).
We'd need a GPU for visual output, if any. And other peripherals (like a GPS receiver) might need their own microcontrollers.
I'm really drawn to this design!
2/2 Fin!