I see three reasons why the modern races split along the same lines as those older , much more divergent groups.  First, the geographical and ecological factors that drove isolation before the expansion of AMH did so again after mostly-modern humans spread over the world.  Second,  those mostly-AMH populations were exposed to many of the same selective pressures as their predecessors, so you expect a certain amount of convergent evolution. Third,  there is reason to believe  that those moderns picked up adaptive alleles from the archaic populations they displaced – so, to a limited extent, they are the the old subspecies.