Proposed resolution:

This wording is relative to N5008.

1. Modify [simd.traits] as indicated:

   template<simd-size-type N, class V> struct resize { using type = see below; };
   

   […]

   -9- If `V` is a specialization of `basic_simd`, let `Abi1` denote an ABI tag such that basic_simd<T, Abi1>::size() equals V::size()N. If `V` is a specialization of `basic_simd_mask`, let `Abi1` denote an ABI tag such that basic_simd_mask<sizeof(T), Abi1>::size() equals V::size()N.

The wording actually requires the size to be left unchanged.