I recently wrote an editorial detailing why I believe the game is still releasing with the Switch day one, so this seems to add further support to that idea. It is possible that this is a first run of adverts that will be updated with new ones with updated dates soon - after all, advertising for the Nintendo Switch is going to eventually be publicizing the actual release date of the system.
As a side note, employees at the store are stating that the system is arriving in the UK on March 19th, something that lines up with a report from Laura Kate Dale awhile back. Either way, we're literally 13 days away from knowing everything we need to know, including the release lineup and date.
For now, let's just sit back and watch this really entertaining video by GameXplain which uncovers the secret in the Let's Play for Breath of the Wild shown off at the Game Awards earlier in December. In the Let's Play, Nintendo's Bill Trinen and Nate Bihldorff show off an unseen part of Breath of the Wild, featuring a quest set in a tropical forest location. The quest is given to the player by a minstrel named Kass who appears to be of a bird-like race and sings a verse pointing the player toward "where the dragon's mouth meets the serpent's jaws." The Let's Play then shows Link traversing through the quest and battling multiple enemies until reaching the dragon's mouth and serpent's jaws, where a larger boss enemy is encountered and defeated.