The subject continues through the eighth verse (89) at the end of which it has been said to comfort the Holy Prophet ﷺ ; فَإِن يَكْفُرْ بِهَا هَـٰؤُلَاءِ فَقَدْ وَكَّلْنَا بِهَا قَوْمًا لَّيْسُوا بِهَا بِكَافِرِينَ (So, if these people disbelieve it, then, We have deputed for it a people who do not disbelieve in it). In other words, it means: If some of your addressees do not listen to you and are, despite having been told about the teachings of all past prophets, bent upon nothing short of denial, then, you do not have to worry - because We have appointed a great people who would say yes to your call, follow your word and make the mission their own, and who would never stoop to the level of disbelief and denial.
Included here are all Muhajerin and Ansar present during the blessed age of the Holy Prophet ﷺ and also all Muslims who keep coming upto the end of time until comes the Qiyamah. And this verse is a fond asset for all such people, as Allah Ta` ala has named them on an occasion which calls for praise by Him:
اَللَّھُمَّ اجعَلنَا مِنھُم وَاحشُرنَا فی زُمرَتِھِم
0 Allah, make us one of them and raise us in their company.