In yesterday's Intel webinar it was stated that AVX512 reciprocal approximations are accurate to 28 bits precision. I guess they should have said this is the goal for reciprocal approximation plus one iterative refinement. Two of us asked about this in the chat but it wasn't answered.
It was mentioned that the reciprocal approximations support double data type for the first time. My take would be that the earlier reciprocal approximations would have required 3 iterative refinements for double, while 2 would be sufficient with AVX512, which may be the reason why compilers for AVX2 and earlier host targets don't choose this method. This was brought up the context of KNL; maybe it implies that KNL still won't have IEEE divide or sqrt instructions, or, if there are such, that they aren't recommended. There seems to be continued tendency to market this aspect of Intel(r) Xeon Phi(tm) in an obscure manner.
I suppose that AVX512 would imply adjustments in recommendations on -Qimf-accuracy-bits usage, but maybe that feature would be even less deserving of attention than in the past.
As to whether -Qimf-domain-exclusion would remain important for KNL, with unchanged value translations, that seems implied by the recommendation to tune on KNC.