I want to remind people there is no indication of the Pixel series removing the OEM unlocking feature in future generations.
All we know is Android moved the primary development platform from Pixels to Cuttlefish.
This is probably due to the fact Android may be required to separate from Google, in which case Google would want to keep the Pixel series as their property.
OEM unlocking doesn't effect potential rights issues, pixels be 'the' android platform may.
Regardless, we won't know anything until its released.