No doubt the IAAF will need to clarify exactly what criteria will satisfy a “women's-only race.”
I am amazed (though perhaps I should not be) by the uninformed views and attempted analogies this ruling brings to the fore, which ignore reality. There is no equating sitting-and-kicking, using a watch and mile markers for splits, monitoring a GPS watch pace reading, or whatever else with women being paced by men known to be significantly faster. What it would equate to would be men being paced by vehicles and I somehow doubt that all those protesting this ruling would support that concept. There is clear scientific evidence that pacers provide significant advantage beyond the attempted analogies noted above. This is born out in the real world, this is why we have not seen major records set sans pacers and even why major record attempts are not made sans pacers. It is also born out in the number of women who have been at all close to Radcliffe's WR (old or new), with and especially without pacers. Allowing men to pace women had made a mockery of the women's marathon WR, just as if it were allowed on a downhill course, on a short course, etc. This ruling is a good move to right that misstep.