From the Associated Press:

“The White House has developed a plan to replace Secretary of State Rex Tillerson with Mike Pompeo, the director of the Central Intelligence Agency, within weeks, a senior Trump administration official said on Thursday…

“John Kelly, the White House chief of staff, developed the transition plan and has discussed it with other officials, the Times reported. Under his plan, the staff reshuffle would happen around the end of the year or shortly afterward.”

For the rest of the story:
https://www.reuters.com/article/us-usa-trump-tillerson/white-house-has-plan-to-replace-top-diplomat-with-cia-chief-u-s-official-idUSKBN1DU23F