A relevant issue: Also it was previously proposed to drop XP support here. Considering that XP support is essentially broken for more than 3 years, I think dropping it is a long overdue. Moreover I believe we need an official policy for dropping OS versions support.
One simplification example: removing XP and Vista support would allow us to use BCryptGenRandom for all Windows targets instead of relying on deprecated RtlGenRandom on non-UWP targets, see this issue.