This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 112e. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
[Accepted at the November, 2020 meeting as paper P2096R2.]
It appears that partial specializations of variable templates are intended to be supported, as 13.4.4 [temp.arg.template] paragraph 2 says,
Any partial specializations (13.7.6 [temp.spec.partial]) associated with the primary class template or primary variable template are considered when a specialization based on the template template-parameter is instantiated.
However, there is no explicit specification for how they are to be handled, and the wording in 13.7.6 [temp.spec.partial] and its subsections explicitly applies only to partial specializations of class templates.
Additional note, July, 2017:
The term “primary template” appears not to be defined in the current wording; the resolution of this issue might be a good opportunity to add such a definition.