IANAE - Rhe thermal runaway of these batteries is a problem. Sounds like the containment bags would only hold a few. What is the Plan B if this fails to to contain them?
As for propulsion-level batteries, there will be many batteries in close proximity. This likely cause a cascade effect. Should the aircraft design include a way to eject these if necessary? Yes - there will be undesirable consequences of this as well. Is there a way to balance the risks from an aircraft vs one of its battery packs falling from the sky? Or do we not use these batteries for propulsion and wait for the next type or generation that doesn’t carry these risks?