As Bryan mentions in https://news.ycombinator.com/item?id=37880669, I would read Matt's post-Intel and post-Google write up of why Intel didn't really invest.

https://pharr.org/matt/blog/2018/04/30/ispc-all if you don't want to follow the comment link again :).

I naively thought ISPC turned into the new DPCPP compiler they’re leaning into with their oneAPI marketing. Are those really different lineages?