So after playing both the Flights and the recent release I can confidently say that playable elites could work in Halo Infinite. As a long time fan since Halo 3 I have always played as an Elite. So far with the way Infinite plays it feels more like a classic game that has evolved. The movement isn’t extremely advanced like Halo 5. I could see an Elite using Grapple shot, repulser, or any of the other equipment. They also have a slimmer body/hit box like they used to in the older games.
343 has also spoke about Player Expression a lot. Playing as an Elite is part of that. Every Halo my proffered species has always been Elites. The customization was great in Halo 3 but lacking in Reach. But with Infinite it would be amazing. Plus it would open up options for some other game modes as well.
An Expansion or Season idea would be based around the Swords of Sanghelios coming in to assist the UNSC. Imagine, a story expansion that starts off with the Banished about to take you out. Then out of no where S.o.S Banshees fly overhead taking out Banished drop ships and you hear the Arbiter on Comms saying he’s there to assist.
To me, and many others playable elites belong in Halo. The whole, Halo Infinite is a “Spartans Story” is no excuse. Reach was a Spartan Story, Halo 3 was a Spartan story, with elites in co-op. Yet both games had Playable Elites. 343 can do it, and I hope at some point playable elites will return.