Yes. WG stated in their article on the Unique Upgrades that new ships would receive one after a few months. The article on the Unique Upgrades (formly Legendary Upgrades) is 404 error right now for some reason.
https://worldofwarships.com/en/news/development/modernizations-x/ @turbo07 found the link that works.
The Unique Upgrades are seen as side-grades by WG and are supposed to be balanced vs using other slot 5 or slot 6 upgrades. They were never intended to make a ship over-powered as it seemed some hoped it would.
So Salem, Harugumo, Stalingrad, Daring, Bourgogne, etc will get Unique Upgrades a few months after release.
P.S. the Unique Upgrade missions are permanent and you get the mission by playing one battle in the ship after the mission is released.