Would be great to have him fight beside Chief again in a few levels.
However personally I don't like being forced to play as more then one protagonist during a main Halo story. Halo 5 ruined that for me.
That's a shame, seriously. There's so much potential for great story telling when two perspective come together to tell it.
Honestly, I know Halo 5 wasn't the best, but look at Halo 2 for a better example. The Arbiter brought a much deeper story then chief could have ever provided, he was arguably a better character in that regard. We love Chief because he's a vessel for us to inhabit, but we loved Arbiter because he was a well developed character.