According to 13.8.3.5 [temp.dep.temp] paragraph 3,

a non-type template-argument is dependent if the corresponding non-type template-parameter is of reference or pointer type and the template-argument designates or points to a member of the current instantiation or a member of a dependent type.

Members of non-dependent base classes are members of the current instantiation, but using one as a non-type template argument should not be considered dependent.