For Scrypt-N, Scryptr mines at 1.6MH/s for N=2048 and degrades about 33% for every step-up in N factor.  The next increase for Vertcoin is not until 2/25/16.

Scrypt-N uses exponential memory increases to work, so regardless of ASIC, GPU or CPU, it will only work for specific N-values for as much RAM as you have available.
I suspect that an ASIC can be made to work by reducing the number of threads, thus allowing more ram per thread, but that only goes so-far, and the devs for Scrypt-N are free to adjust N to any value they like... Leaves them the option to push the N value higher than the "currently available" ASICs can support.
Working through a HW change to add RAM is much more time consuming than just changing a variable in the Scrypt-N algorithm, so they can easily keep-up with technology and progress.