Hi !
It is normal that some Audio cable (only) company make a new series of cables every two or even one year. Naim is not a company which produce such a cables. Cables, which are known as Naim cables like Naca 5, Snaics etc. are produced by other company(s). One was BICC as my memory serves me well, but I am not so shure that they still produce cables for Naim, because they was sell Naim designed cable to Linn marked as BICC design, which is not. So partnership is compromised after that. Ofcourse, Naim was designed a better cable after that happened and now we have Naca5 which was made by some other company, I think.
On the other side, I agree that after ten years is time for change, but that is only a psychological factor. The question is, how much will cost a better/new cable, because Naca5 IS a good cable and only a very new tecnologies can produce a sinthetically tested better cable, but in a mid Naim system I think that "new" cable wouldn't be significant improvement. Just take a look on Naca4 and Naca5 differencies. Is Naca 5 so much better than 4? If Naim would owned a cable company, then we can expect a new cable every few years, until then nothing will drastically change. The other problem is quantity and only if selling of black boxes raise in all countries like New Zealand/per citizen head, Naim will make an order of hundred of thousands cables and in that case investing in research of better cable will have sense.
But who knows, maybe they prepare a black cd cable or even Naca 6.

Ozren
p.s. sorry on bad english