This has been talked about plenty, trust me. I think most people would love to see an ODST style FF in halo again, as it was/still is the most popular one. It won't happen in Halo 5 for numerous reasons, but I hope there is an ODST style FF in Halo 6 though.
Mmmm... Classic firefight. I would love that for Halo 6. I enjoyed the Firefight in Halo: ODST, and I really like the firefight in Halo: Reach for all the options we were given to tweak the scenarios. If those were in Halo 6, that would be great.