Square on crack

I'd laugh my butt off if a shadow heartless appears

I think it would be better off without the Easter eggs.

Hell yes give him a Kingdom Key.

 

Or a STICK!

I think it would be hilarious to see an organization XIII-esque coat that you could pass by in a shop somewhere and you can press an option button telling you, "costume on sale, 13% off"

Playing dearly beloved on the piano in Nibelheim would be pretty awesome

The piano sounds cute, or some rare dialogue you can get after spending a night at the golden saucer inn after doing some matches in the Battle Square with Cloud (Or else something oddly specific) about having a strange dream about working for the lord of the dead.

Cloud should bandage his sword at one point and ask Vincent if he can borrow his cape for a bit. X)"

I think it would be great if Dearly Beloved was played on a piano anywhere in the game.  

It would be nice if we had the kingdom key but that sound very optimistic I believe it will be something hidden like dearly beloved playing on a Piano on the beach or something

Sora (kh3) as a secret boss, keyblade or kh buster sword as an unlockable weapon and dearly beloved on a piano.

I think a really nice and subtle Easter Egg would be to just waltz into a building or a shop, and faintly, you can hear the tune of Dearly Beloved on the piano, be it on radio, or someone actually playing the piano! That'd be a pretty sweet Easter Egg!