Sony Pictures Animation has created both fully-animated (Open Season) and live-action-plus-CG (The Smurfs) in the past, so it's hard to say which way a Sonic movie, should it ever be made, would go. If it's the latter, we're telling you right now Sony, making it dark and edgy - complete with Dr. Robotnik/Eggman torturing someone - has already been done.
Sonic the Hedgehog - The Movie. Coming sometime. Possibly. Running time (if it happens): fast.