I sure hope it's true that Boeing has engineered a fail-safe solution to the Dreamliner's self-immolating battery problem, but their confident claims have that disturbing famous last words ring to it:

Two top Boeing executives delivered an unflinching defense of the 787 Dreamliner in a Friday morning news conference in Japan... “We’ve been able to demonstrate that no fire is possible,” [Boeing VP Mike] Sinnett concluded.

Not that it'll keep me from flying in a 787, and this is probably more of a PR issue than a technical one. But if there's one thing we've learned from history, it's that the gods hate hubris and love irony.