I would really hope they bring back the Sangheili for Infinite. Lorewise, with the SoS and the Arbiter allying with humanity, it would make sense to have Elites and Spartans working together. I do hope if they do so, we can have greater customization than before because it was disappointing in Reach. I hope 343 listens since this discussion has been accumulating for years now.
Anvil station, a UNSC space station introduced in Halo Offline, has Spartans and Elites training together in War games simulations. Although in the game itself we didn't see Sangheili, in canon, they were participating. The introductory video of the game even shows Spartan-IVs with Elites fighting against other Spartan-IVs with Elites. Even the Shadow of Intent
was equipped with the War games technology by Humans. I think it makes sense for Spartan-IVs and Sangheili to work together, putting aside the lie that the whole war was and starting anew. Fun over lore, but in this case, both are reasons for Sangheili to return to a playable state.