Comparing him to other great players with short careers, I don't think he measures up well. Gale Sayers made the Hall because he was a unique talent who changed the game. Some people have made that same argument for Bob Hayes, but he has not made it, and probably will not. Terrell Davis, as I mentioned, won two Super Bowls, which gives him an advantage over Sharpe.
The bottom line is that a player can't make the Hall based on what he MIGHT have done if he had a full career. It's a drag, because Sharpe would've put up some incredible career stats, especially on that offense with Favre throwing to him.
He did have kind of a difficult personality, though, so who knows, maybe things would not have worked out that way. It would not be hard to imagine him demanding more money than what Wolf would've been willing to pay. Of course, then he would've put up incredible numbers for some other team.