I found a secuence in the old and the new Halo trilogy.
In Halo CE we found a new “planet/instalation” that was the Halo. And in Halo 4 (that is the first game of the 343 trilogy) we found a planet, Requiem.
In CE we also found a new enemy, the flood; and in Halo 4 the prometheans.
In Halo 2 we have 2 campains, one with Master Chief and the other with the Arbiter and in Halo 5 we do the same thing. We also have a disintegration of the covenant, in Halo 2 with the Great schism and in Halo 5 the prometheans finishing their alliance with Jul 'Mdama. And in this 2 games we have a boss, Tartarus and the Warden Eternal.
With all of this we can expect about the Halo 6 plot. If we continue with the secuence we can say that in Halo 6 important characters will die, we will have the end of a faction, and some missions with allied sangheilis and the arbiter (yey).
Sorry for my english.
While I do agree that there have been many similarities between the old and new games, Halo 6 may not be the final installment in the reclaimer saga since 343i has stated that their original plans for a trilogy were cancelled, and are now making as many Halo titles as needed to properly tell their story.
Still, you may be right if some things in Halo 6 and Halo 3 are similar. I just wouldn’t expect Halo 6 as a conclusion to the reclaimer saga.