I believe it's not only CPU miners that are at stake here. Even signatures could be validated 2-4 at a time, on the same subroutine, to get SIMD benefits. So scaling is affected as well. It would need the main routine to be adjusted accordingly instead of sending 1 for processing (per thread) to 2-4 (per thread) and expect back 2-4. Heck, even cracking speed could be improved.
Signatures should eventually be verified on GPUs (or similar SIMD units that get integrated into CPUs in time). That will happen when it is needed. CPU SIMD instructions are kind of interesting but also kind of narrowly-targeted. Processing large amounts of data in a fixed pipeline will still be more efficient on GPU-type architectures.