وَرَبُّكَ ٱلْغَنِىُّ ذُو ٱلرَّحْمَةِ ۚ إِن يَشَأْ يُذْهِبْكُمْ وَيَسْتَخْلِفْ مِنۢ بَعْدِكُم مَّا يَشَآءُ كَمَآ أَنشَأَكُم مِّن ذُرِّيَّةِ قَوْمٍ ءَاخَرِينَ
Wa Rabbukal ghaniyyu zur rahmah; iny yashaaa yuz hibkum wa yastakhlif mim ba'dikum wa yastakhlif mim ba'dikum maa yashaaa'u kamaaa ansha akum min zurriyyati qawmin aakhareen
Your Lord is self-sufficient, the master of mercy. If he wills, he can take you away and bring whomever he wills to succeed you, just as he raised you from the descendants of another people.
God is called self-sufficient and holder of mercy in one breath, and the pairing carries the weight: nothing in the mercy answers a need of his own. The succession described is already a fact about whoever reads it, since every people now standing took the place of an earlier one. What could be heard as a threat is put as something that has happened before.