Proposed resolution:

This wording is relative to N4527.

1. Modify [futures.unique_future] as indicated:

   R future::get();
   R& future<R&>::get();
   void future<void>::get();
   

   -14- Note: as described above, the template and its two required specializations differ only in the return type and return value of the member function get.

   -15- Effects:

   • wait()s until the shared state is ready, then retrieves the value stored in the shared state.;

   • releases any shared state ([futures.state]).

   […]

[ 2016-08 - Chicago ]

Thurs AM: Moved to Tentatively Ready

The standard is usually very explicit on when a shared state is released, except for future::get for which it only states valid() == false as a postcondition.