Nrt -> hkg

Hello all, I thought this would be a good place to ask my question.

I just started working for Delta, and was planning on flying to Hong Kong with my travel companion, non-rev, leaving from Atlanta on December 28. Currently for the NRT -> HKG leg, the flight has a business/first availability of 6 and coach availability -1 with me and my friend currently 6 and 7 on the list of non rev.

What is the likelihood that this flight stays open enough for us to get on? Does it usually fill up pretty heavily or anything? I was getting kind of worried about how easy it was to get in/out of NRT, especially if it has a tendency to fill up right before getting on as it is not something I can just check and hold out for another flight being so far from home and it being the only flight out of NRT to HKG....

Anyways, I really appreciate any help on this matter. Have a good day!