Here is John Wesley's view. He interprets the casting as something like a metaphor: "That is, were abolished for ever; for neither the righteous nor the wicked were to die any more: their souls and bodies were no more to be separated. Consequently, neither death nor hades [the KJV translation of hell] could any more have a being."
Exactly as when final judgements are rendered after Christ returns there will be no more death nor the need of the grave (hell).
Rev 2:11 He that hath an ear, let him hear what the Spirit saith unto the churches; He that overcometh shall not be hurt of the second death.
Rev 20:14 And death and hell were cast into the lake of fire. This is the second death.
Rev 20:15 And whosoever was not found written in the book of life was cast into the lake of fire.
Rev 21:7 He that overcometh shall inherit all things; and I will be his God and he shall be my son.
Rev 21:8 But the fearful, and unbelieving, and 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.
Strong's Exhaustive Concordance: Hell
Hebrew # 7585 Sheol, Hades, or the world of the dead, grave, hell, pit
Greek # 86 place of departed souls, grave, hell
Hell only means the grave as through Christ we who are His own at His coming have victory over the grave in the resurrection as being overcomers of this world, 1Corintians 15:54, 55. Hell/grave will be cast into the lake of fire as there will be no more need of the grave after everyone has been resurrected for the purpose of God's final judgement on the last day when Christ returns. The second death means those who are Spiritually dead listed in Rev 21:8 that have rejected truth and also those who preach another gospel as no truth is found in them.
John 5:28 Marvel not at this: for the hour is coming, in the which all that are in the graves shall hear his voice,
John 5:29 And shall come forth; they that have done good, unto the resurrection of life; and they that have done evil, unto the resurrection of damnation.