The NTSB update is interesting, especially in juxtaposition with this latest lively lithium incident. An announcement that "we'll be wrapping up the data gathering in March, and then get on with writing the report" must mean "and we've not found any urgent safety action points yet" - assuming that if the smoking gun had been found, some more timely interim advisory would have been issued.
Meanwhile, the bleeders continue to get toasty.
From which, one deduces:
1. The NTSB still doesn't know the ultimate cause of the failures
2. The stated March deadline is now likely to be extended
3. They're happy that the Boeing containment fix is adequate to ensure a/c safety
4. We've still got no idea when the no smoking rule for Dreamliners is likely to be enforced
The saga drags on...