The likely replacement for his workload is probably a group effort. The one player who is closest to Johnson in ability, and also style, is Andre Ellington. While he will be likely just part of the solution to deal with Johnson's absence on Sunday, don't be surprised if Ellington becomes the one long-term answer at that position.
Remember, it was only a couple of years ago when Bruce Arians said the Cardinals would build the offense around Ellington. He had glimpses of brilliance early in his career and even in spot duty recently. But Ellington couldn't stay on the field.