Yeah I wouldn't want Prince as an actor.
But he would at least be a good choice for dubbing the guitar parts, though having the actor be someone who can actually play the guitar would add to the authenticity.
Still they would want someone with star power so if it ever gets made it will probably be a high profile african american actor. Will Smith wouldn't be a bad choice, he's a really good actor actually. He's a little old for the role but compared to the aforementioned actors he looks like he could pass for being in his 20s and he's the closest to Hendrix in physical resemblance.
If they picked Eddie Murphy I wouldn't be able to control myself.