Yes, you probably need to think about that topic title for a second, but really when you think about it, it doesn't sound that odd. See your Smartphone or tablet already makes use of what is called Big.little architecture. Small processor cores that are used when energy efficiency is needed, and fast cores when performance needs to kick in.  

Well, a set of rumors has been floating around the web for a while already that this might actually happen for Desktop processors. As currently, all cores are equal right? Intel could be mixing expensive and inexpensive cores that way, driving down cost.

Rumor has it that Intel is working on CPU cores of different types and performance for the desktop, this is developed under the codename "Alder Lake-S". Much like Lakefield, where you stack slower and fast cores for better efficiency (Lakefield is intended for mobile use).

Taiwanese website PC_Shopping spreads is a rumor that Intel also combines different CPU cores with Alder Lake-S in the desktop. Eight "small" and eight "large" cores would be merged together, add to that a graphics unit, all in one package. According to the leaked slide, a CPU with 8+8 big.little cores would have a TDP of 125 watts. The socket design would be called  LGA 1700 into the equation (yes, a new motherboard required). The process technology would be based on Foveros technology, where Intel is stacking die's onto one package (think HBM2 on a GPU).

It's an interesting concept. However, history has learned that stacking chips is very yield sensitive, and thus often more expensive than intended.

Processor cores mixed for desktop: Rumors about Intel Alder Lake-S processors with 8+8 cores