Velen said he had a vision of Anduin wielding the Ashbringer, the ultimate Paladin sword. Aka, Anduin becoming a Paladin like Arthas.
Garrosh compared Anduin to Arthas (although saying it was himself after) “
There was another golden-haired, beloved human prince once. He was a paladin, and yet he turned his back on the Light.”” where Anduin replied “I am NOT Arthas!!”
Anduin is getting longer hair, like Arthas.
Blondes with blue eyes?? Devoted to the light?
In the announcement trailer, the entire scene is basically what happened back in Lordaeron. A raven flies into the throne room to transform into a mage, called Medivh, who warns the King, Terenas about a a threat and then theres the blonde son. In the cinematic, a Raven flies into the throne room to transform into a mage, called Khadgar who is Medivhs apprentice, to warn the King, Varian, about a threat.
My son, the day you were born, the very forests of Lordaeron whispered the name Arthas.
My child, I watched with pride as you grew into a weapon of righteousness.
Remember, our line has always ruled with wisdom and strength. And I know you will show restraint when exercising your great power.
But the truest victory, my son, is stirring the hearts of your people. I tell you this, for when my days have come to an end, you shall be King
- King Terenas Menethil II, the Last True King of Lordaeron.