Addressing your last sentence, I am actually a GPU programmer by trade. GPUs are my specialty, and much of my professional work has been in Nvidia's CUDA
But AVX-512 is a real step forward, if you look at the price/performance ratio for real-world workloads. So AVX-512 is the focus of NN-512
GPU cloud compute is almost unbelievably expensive. Even Linode charges $1000 per month, or $1.50 per hour (look at the GPU plans: https://www.linode.com/pricing/#row--compute). It's really hard to keep that GPU saturated, which is what you need to do to get your money's worth
An AVX-512 Skylake-X cloud compute instance costs $10 per CPU-core per month, or 2 cents per hour, at Vultr (https://www.vultr.com/products/cloud-compute/). It's easy to saturate that core
Think about it this way: a GPU is really just a cluster of SIMD units with fast memory. A GPU thread variable is just like a SIMD lane, and a GPU warp variable is just like a SIMD vector register
Nvidia's SIMD pseudo-instructions are called PTX and they are like a 1024-bit version of AVX-512. An AVX-512 core is like a general purpose CPU with a 512-bit GPU core built in
So paying for a single AVX-512 core is like paying for part of a GPU (16 threads), plus the general purpose compute you need to keep that GPU part supplied with work