He will replace Ruth Bader Ginsburg and be promoted to CJ when the truth about Roberts comes out.
He needs to be AG first and train others to replace him when he gets a nomination to the USSC.
I would not want to see a natural leader like Cruz shunted off to the side on the Supreme Court. We have plenty of able jurists which he could appoint when he's in the Oval Office. But not all able jurists have his leadership ability.