SoS -
There is a physical barrier between cells 2 & 3 and cells 6 & 7, however, only a small air gap separates cells 1 & 2, cells 3 & 4, cells 5 & 6, and cells 7 & 8. I guess that could limit damage to just half of the battery, but I suspect that four burning cells on one side of the physical barrier will easily supply enough energy to ignite the four on the other side of the barrier. In fact, I think Boeing has proven it - twice even.