Verbose Mode is dropped on macOS Sierra?

System Integrity Protection (SIP) disables changes to NVRAM. In order to make changes, you need to temporarily disable SIP by doing the following:

1. Boot into Recovery Mode. (Hold Command-R from the time you start your machine until the Apple logo appears.)
2. Open the Terminal from the Utilities menu.

3. Enter the command:

   csrutil disable
   

4. Reboot and you will be able to run your desired commands from within a normal session.

5. It's strongly recommended that you re-enable SIP when you're done making adjustments. To do so, run this command:

   csrutil enable
   

Note that if you intend to make a lot of changes to NVRAM, you can leave SIP enabled but disable NVRAM protection by running the following command from the Recovery Mode Terminal:

csrutil enable --without nvram

Again, you will need to reboot for changes to be effective.

As best I can tell in Sierra, it is still possible to: sudo nvram boot-args="-v" without disabling SIP.

However, the interesting thing is that while Vervose mode works at boot as it always has, it no longer displays anything at shutdown.