To me, there are two ways to look at a national hymn....1) the piece is accompanied by lyrics (star spangled banner, god bless america, etc) so the melody of the song needs to be "singable" by the average person. Obviously, the other way is the song does not have lyrics so you can do whatever you want with it.
So, with the above being said, this piece seems structured to me like it can be accompanied by lyrics. The only exception to that is the very beginning. Up until :17 of the piece, there is a good amount of layering with no clearly defined melody like later in the piece (starting at :24). If you are going for the lyrical feel, then I would scrap the first 16 seconds in favor of starting with the low brass cord and percussion or maybe doing a short introduction to that with just percussion. I see no problem having the same percussion part from their initial entrance to :24 being the start of the piece then coming in with the low brass part with a repeat of the percussion part.