I see Tillerson as more of a power behind the throne. Very much a kingmaker. If Trump is, somehow, persuaded to resign (which I don't think will happen), Tillerson is the Al Haig of the transition, and will emerge as Pence's indispensable man.
An Al Haig analogy might be effective for a Chief of Staff; his time at State, however, isn't looked back on as particularly good or effective.
Al Haig ran the entire government during the latter days of Nixon. His real role went far, far beyond his title.
Not only that, but Tillerson seems to be building up allies with Mattis, Kushner, Sessions, and the like, although he and Kushner have had tensions.