We don't need Fournette to do the latter. He'd just fit it perfectly and could be a generational talent. There are other backs in this draft who could fit into a power run game built to utilize the play action and open up the intermediate and deep routes for Cam's big arm.
We definitely should be adding some more short passing game into our offense, but not as a foundation of our offense. It should come from the slot position which hopefully is filled by the addition of Shepard or by a draft pick, ideally not a top 10 pick in McC or even at 40 though. If we want our offense to incorporate the short passing game as a feature then Cam needs to improve quite a bit there.
I think he lost weight will help get his speed back. He did look slowed last year. But he also had ankle problems and was beat up.
We need a traditional running game that can operate without Cam's own ability to run. Fournette and Stew would beat the piss out of a defense.
Receivers need to step up as does our OC.
Cam made some bad reads and held onto the ball a lot last year. But he knows how to ball.