The last part has me scratching my head a bit. I've been involved in a large number of resaonably complicated engineering efforts in the past and one element of this whole BeV thing keeps gnawing at me.
I think we may be taking for granted the ease/difficulty in building high quality long life batteries that are safe based on the relative ease with which Tesla has, and continues to, accomplish the task. Where I think this risk association/anology is weak is the fact that Tesla fully owns the problem from pack integration to protection to cell design. They have the ability to simultaneously attack battery degradation and pack cooling and physical damage survival and and and while legacy OEMs have ridged engineering structures that rely heavily on their existing vendor base. These OEMs may very well pull off a well made battery that does not suffer from long term performance or safety issues. Alternatively, they may be like Zero where you have a hard time giving away a five year old bike (I exaggerate but the depreciation is staggering).
Time will tell but this is most certainly not a given for me that MB, VAG, GM,,, will perform as well or better than Tesla on the core element of their car's safety and longevity.