The new KH2 FM+ Secret Ending

[Fynn]

I have a thory...

The brown-haired guy - as stated previously - is a young Xehanort. He battles with baldy and beats him. But the man uses the last of his strength to somehow... become part of Xehanort, leave what's left of him inside the knight. Then Xehanort lost his memory and landed in Radiant Garden. But the bald man's piece inside him remembered his aim - Kingdom Hearts and that's why Xehanort was so obsessed with studying the Heart...
The "Memories of Xehanort" mentioned in the original secret ending might be an semi-title ("Kingdom Hearts: Memories of Xehanort") if this game won't be KHIII. And yes - I think Xehanort will be the main character of this part.

Just a theory, you know...