Upcoming Winter Update

It is stated that all memory and evidence of the existence of the 6th hero was eradicated. It actually seems less icky this way. They didn't just stick a new one in.

Altering established story facts is precisely what a retcon is.
Yes, they did just stick a new one in, using a trope that has already been ridden to death: memory loss.

Maple Story's story has long reeked of patchwork and lack of forward thinking. To doubt that this Hero was last-ditch effort to generate interest is to give credit to a team that had to delay a reveal countdown.

It says that 'the secret of the Black Mage's sealing will be revealed', so I think that the story we've heard so far (Luminous being the last to enter the battlefield, him and Freud sealing the Black Mage away) is not all there is to it anymore.

Fixed for accuracy.

Wizet really needs to get past the past and start creating story content that actually advances the Maple World. Instead of introducing new complications and unnecessary details, they should adjust the existing Heroes' backstories to interweave and stay consistent then let them be.

We KNOW how the Black Mage was sealed.
It's about time we moved on to his unsealing and the aftermath.