So why didn't Allah Almighty directly Say in the Noble Quran that Hell will eventually be emptied then?
Well He did indirectly say it in the "So what about Hell then? How long will the worst of the creation reside in it?" section above. I believe that the reason why He, the Almighty, didn't DIRECTLY mention it in the Noble Quran is because He probably didn't want Mankind to be counting on serving a time in Hell and then get permitted in Heaven, hence it wouldn't sound strong enough or scary enough to stop them from sinning, and would probably then cause them to be more careless.
He probably also wanted to show the Holy Image of His Punishment and Angry Side to make it clear to Mankind that Hell is not a joke and it is not to be taken carelessly.
Allah Almighty didn't share everything about Him and His future Plans with us. He made this clear in the Noble Quran by Saying: "...of knowledge it is only a little that is communicated to you...(The Noble Quran, Noble Verse 17:85)"
We also know that He Has a Book that is sitting with Him on His Throne: Narrated Abu Huraira: "Allah's Apostle said, 'When Allah completed the creation, He wrote in His Book which is with Him on His Throne, 'My Mercy overpowers My Anger.' ' (Translation of Sahih Bukhari, Beginning of Creation, Volume 4, Book 54, Number 416)"
Maybe He has some Holy Plans written in that Holy Book that we are not aware of. So, it wouldn't be surprising that the steps for emptying Hell from Allah Almighty's Creation is one of His Holy Secrets or Holy Things that He didn't choose to directly share with us.
Back to 'Hell will eventually be empty according to Islam' section.