I'd think 343 could probably make use of Installation 07, whether it be a part of the map from the campaign or generally an area within Installation 07. They don't have to be confined to just the area of the ring that Chief'll be fighting in, and they could go deeper into the ring's inner workings or go higher into the highest peaks of the installation. Of course, I think its more probable that if they were to take something from the Campaign it'd be an already crafted area of the map, but there is nonetheless potential in making maps centered in Zeta Halo. The Campaign is supposedly bigger than 4 and 5 combined, which is fairly big(and ambitious), so I would assume that they could 100% squeeze more out of making those areas than just a Campaign level. Unless the Campaign is ever-evolving with their "10 year plan", I'd assume most of the Campaign will relatively stay the same throughout the years while DLCs get added on. If they were to make something like Spartan Ops or Firefight like you said, I wouldn't doubt reusing some areas of the Campaign's semi-open world to serve for their levels. Actually doesn't sound bad at all, but we still have to see it in practice first.
Maybe the next Forge World will be set on Zeta Halo. I would like that.