Revelation 21:4 indeed says that the old order of things has passed.....except, I guess, in your ever burning "Hellfire".
The wicked will experience eternal death because death is the most merciful fate a loving God could impose on those who insist on breaking his law and reaping the resulting unhappiness. They will be put out of their misery and not make others miserable either. [Revelation 21:8][Psalm 37:20] [Romans 6:23]
"The wicked will experience eternal death because death is the most merciful fate a loving God could impose"
What you are not taking into consideration is that in the judgment of those whose names are not found in the book of life, God is not acting as a "merciful, loving God" but as a just and righteous judge who is meeting out the penalty just as He warned He would. In Rev. 16:17 the fateful phrase "it is done" ends His grace and mercy for those who haven't trusted Christ for salvation. Now they get what they deserve just as those who have trusted Christ get what they don't deserve. Both get eternal life, just as they wanted.