@alex-m1, you shed an interesting light here. Yes, MTK's wearable solution ("Aster") is a multi-die solution. How that might change the SoC narrative is a good story to follow. Thanks for pointing that out.
>> There are many SoC companies out there. Few have memory technologies....
Multi-die integration is starting to become interesting. XMOS is selling a mult-die mcu for less than $5 , media tek works on it's new wearable soc using mutiple die tech(and it has a done an impressive multi-die integrated microprocessor for low end phones for $3).
It is true that the flash process will add cost to the integrated solution, but the advantages outweigh the added cost. Having a single die instead of two reduces the system cost and increases the reliability. It also reduces the footprint required on the circuit board. The flash will usually be more than half the die so you should think of this as adding logic to a flash chip instead of adding flash to a microcontroller. The disadvantage is that the feature size of the logic will be lagging the industry in the combined process, so your logic will be larger than it would be on a stand alone chip. As mentioned, the speed of reading and writing the flash will improve since it does not go off chip.