The Pascal architecture supports the page migration engine required for unified_shared_memory, as indicated by NVIDIA:
The limitation was introduced in D54493 which justified the cut-off by the requirement for unified addressing. However, Unified Virtual Addressing (UVA) is already available with sm20 (Fermi. Kepler, Maxwell). Unified shared memory might even be possible with these, but with migration of entire allocations on kernel startup.
To be sure, I enabled the tests for a Pascal GPU which finish successfully.