That is exactly what it means. The Lake of Fire (Hell) is in "outer darkness" where there is "weeping and gnashing of teeth.
Do you even know what that means? That word "hell" in that verse is actually "Hades". So in what sense will Hades be METAPHORICALLY cast into the Lake of Fire? Since Hades is the present abode of the unsaved and lost, when they all stand before the Great White Throne, they will represent the contents of Hades. And when they are all cast into the Lake of Fire, then Hades has no further use, therefore it is metaphorically cast into the Lake of Fire. Just as Death is metaphorically cast into the Lake of Fire. There will be no more death on earth, therefore no more need for Hades (the place of departed souls and spirits who are not in Christ).
The Bible calls the lake of fire the second death. There's no reason to complicate the scripture by bending meanings to suit what you believe they symbolically mean, especially when there's no evident reason to prefer an alternative to the plain text.
Revelation 21:8
8But the fearful, and unbelieving, and the abominable, and murderers, and whoremongers, and sorcerers, and idolaters, and all liars, shall have their part in the
lake which burneth with fire and brimstone: which is the second death.
For example, you would have us believe death isn't death just to protect
your eternal torment doctrine. See how that doesn't really protect the integrity of the scriptures? Annihilationism is sola scriptura.