This post, it is full of wrong.
Now the Arbiter clearly survives Halo 3 and is even in a book after Halo 3. The Arbiter finds out the truth about the godhood of the forerunner in Halo 2 and starts the Great Schism, because of this many elites leave the Covenant and the Brutes take over as the lead warriors. The "Covenant" in Halo 4 are called the Storm, essentially a rebel bunch of Elites who wanted to still worship the Forerunner, unlike the Arbiter.