I found this images posted on another forum:

Apparently someone from Sonic Retro found them on the Sonic 4 site before they were taken down. Of course they could also be hoaxes. 

I'm thinking the "???" will be either Eggman or they'll start listing badniks. Doubt it will be Tails or Knuckles since they said Sonic only. I am kind of hoping for Tails and Knuckles to show up in later episodes though.

And I don't mind the homing attack being in. I mean if you want to get technical you could use the homing attack in Sonic 3D Blast with the help of a shield. And that game did appear for the Genesis so it's still totally retro! If people really don't like it then don't press the jump button again after your in the air.

Also since this takes place after S3&K and the speed sneakers power up was mentioned I'm really hoping for the elemental Shields to make a return. I miss those things.