The 2018 GSS data has been released. As in 2016, the number of young, virginal men (relative to women) has increased, which weighs toward interpreting this as a real trend rather than a blip. Thus, it seems that hypergamy may exist in a particular subset of the population.
It’s still not plausible to blame the Sexual Revolution, given the timing, but more recent factors (e.g. online dating) may deserve some attention. I still don’t believe that online dating is the real explanation, given that the data from OkCupid show relatively egalitarian outcomes.