[averagewall]

It won't go away for the same reason pounds and miles won't go away - people who know it can't be bothered learning something new, and people who are learning it aren't influential enough to cause change. Avogadro's constant is not in any way fundamental. It exists to reconcile the two different mass units that chemists use - gram and amu.

With the 2018 SI change, Avogadro's constant will be defined as an arbitrary number without any physical basis, and the amu will be a constant multiple of the kg. No more 1/12 the mass of carbon 12.

Of course we'll still need a way to represent large numbers, but there's no fundamental reason it has to be such a complicated number. It could be exactly 10^24, for instance. Again, I agree this isn't going to happen because of legacy inertia.