“Another advantage to the larger 4680 cells is that (I hope) they may be able to connect each individual cell to the battery management system instead of entire rows.”
I can’t speak for every application but it is my understanding that each cell is monitored for temperature and voltage. Current is measured for each series grouping.
Much to my surprise I recently learned they do NOT really monitor each cell and it is because of economics (would require additional wiring and connections to each cell). One bad cell and you can lose 49 or 99 good cells. That sucks from an economy standpoint and as you know that is forever more dead weight (little less than 50g per 18650 cell in a Tesla).
This came from a PhD who works at a high level in the industry doing testing, but to be clear I do not know for certain and am only going by what I have heard from others.
There are many potential failure mechanisms for a battery pack and/or the vehicle overall. The most problematic for the industry are the internal failures that are primarily related to quality control in my opinion by 3rd party manufacturers in China like the recent spate of LG battery fires that have caused several recalls of energy storage systems in Europe and Australia.