Is Johnny Cash rolling in his grave?

After retiring from acting, Joaquin Phoenix seems to be making a rather unexpected career change: he wants to try his hand at rapping. Call me cynical, but I can't see him doing a transition from Johnny Cash (whom he was fabulous as in Walk the Line) to the likes of Eminem. And if his career as a rapper falls through, I'd hate to have to see him crawl back to acting with his tail between his legs (is that the crawl of shame, maybe?).

Personally, I think he should have remained in acting, because he had proven himself quite worthy, and was capable of great accomplishments.