The product known as The Elder Scrolls Online: Tamriel Unlimited is no longer available via digital retailers (ESO Store, Steam, PSN, Xbox Store, etc) and is no longer being produced for physical retailers.
'You might have already noticed, but we've changed which versions of The Elder Scrolls Online are available for purchase in stores. Players shopping for the game online or those checking the expansions may have already noticed one of the first changes for The Elder Scrolls Online that replaces one of the products with another that includes Morrowind and the base game. With the launch of #Summerset and Update 18, we’re making a few changes to the way you can acquire Morrowind, get the Warden Class, and access PvP battlegrounds in #ESO.