What will happen after the people of Paradise enter Paradise and the people of Hellfire enter Hellfire? And will God create other peoples in the world who sin and repent?

What happens after the Hour is established and the people of Paradise enter Paradise and the people of Hellfire enter Hellfire is part of the Unseen, known only to Allah, Glory be to Him, and there is no way to know it except through the texts of the two revelations (the Quran and Sunnah). We do not know of anything mentioned in them concerning this matter. However, what we are absolutely certain of is that Allah the Almighty is capable of doing anything His will inclines towards, for He, Glory be to Him, is the doer of what He intends; nothing in the heavens or on earth can frustrate Him.