Judging from PI's description, I'd say it's a hidden upgrade path of some sort with pocket infinity. I know bungie are pretty in depth with secrets etc, but I think this is simpler than we are making it out to be. Or they are just holding off until H5 release....as someone said earlier, there's a strong chance something may be revealed a week or so in advance of H5's launch as a means to keep players. H5=HALO 5 btw, I figured the forums that abbreviates literally everything would know that. My bad.