Nokia just released its model 9 Pureview smartphone with 5 rear cameras and it looks like the number is about to double soon. Xiaomi and Light are working on smartphone camera arrays that could integrate upward of 10 cameras, and the plan is to integrate them in both affordable models and premium ones.
https://www.notebookcheck.net/Xiaomi-Light-collaboration-paves-way-for-affordable-multi-module-smartphone-cameras.410956.0.html