Unfortunately I think it is just the TV cable coax. the HoA frowns on aerial TV antennas and I think this was pre-positioned (with a run of Cat 5 as well.... weird) to mount an antenna in the attic. Not sure if I can put a HAM stick or something in the attic, but I suppose it is a possibility.
I need to run some A/V cable back down, and the chase I want to use is little bit inaccesible along with the ret of the ttic, Like you I think I am going to run some boards up there so I can crawl around easier.