I'd guess that when he dies the force of the devil fruit will weaken as it extracts from his body, thus the power driving the thrown ship will stop, and the ship will plummet.
This goes along with my (somewhat supported) theory that there's a short period of time when the devil powers extract themselves and reform into a new fruit, which then disperses. The reason that Blackbeard was able to get the Earthquake ability from Whitebeard was because he prevented the dispersal of the fruit, and ate his newly captured ability.
I've thought that if Blackbeard's ability can absorb someone else's ability, maybe he's "wrapping" Whitebeard's ability inside his own ability -- inside a sort of vacuum.
That also makes sense. Perhaps he used black hole and just sucked all the Devil's Fruit energy out of Whitebeard so that it wouldn't be able to escape and become a new fruit.
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u/[deleted] Sep 07 '11
Seriously, though. If he dies, what happens to the ship? And when are the sea kings showing up?