John is speaking of the grave....and death in these verses. Everytime you see the word Hades.....substitute grave. Strong's #86.
Using scripture to explain scripture, I look to these verses:
Mat 27:52 The tombs were opened, and many bodies of the saints who had fallen asleep were raised; Mat 27:53 and coming out of the tombs after His resurrection they entered the holy city and appeared to many.
Joh 11:11 This He said, and after that He *said to them, "Our friend Lazarus has fallen asleep; but I go, so that I may awaken him out of sleep." Joh 11:12 The disciples then said to Him, "Lord, if he has fallen asleep, he will recover." Joh 11:13 Now Jesus had spoken of his death, but they thought that He was speaking of literal sleep. Joh 11:14 So Jesus then said to them plainly, "Lazarus is dead, Joh 11:15 and I am glad for your sakes that I was not there, so that you may believe; but let us go to him."
I can see how some folks see these verses pointing out an end to death, but the Holy Spirit NT authors don't seem to see this shift:
Heb 9:27 And inasmuch as it is appointed for men to die once and after this comes judgment,
Rev 20:6 Blessed and holy is the one who has a part in the first resurrection; over these the second death has no power, but they will be priests of God and of Christ and will reign with Him for a thousand years.
It looks to me that we all die once. The second death - the permanent one - is the one that Jesus frees us from.