It'd be pretty cool, and would make sense since he's already in Dimensions.
Yes, please! I want Silver and Shadow minifigures!
Depending on the success of the movie, I can see this happening. If we're doing sixteen minifigures, we could get:
1. Sonic 2. Super Sonic 3. Tails 4. Knuckles 5. Amy 6. Eggman 7. Cream and Cheese 8. Shadow 9. Rouge 10. Silver 11. Egg Pawn 12. Infinite 13. Vector 14. Espio 15. Charmy 16. Blaze
Big would probably be too big to fix in a minifigure collectible bag, though.
a Tails figure would be awesome!
I'm not sure how'd they create a piece for his tails, though. He should have short legs, as per LEGO Dimensions.