What will be Pope Francis’s ‘summer surprise’?

If (as rumored) Cardinal Muller is out this summer as Prefect of the Congregation for the Doctrine of the Faith, who will replace him?
From What will be Pope Francis’s ‘summer surprise’?, a June 7, 2017, report on the latest “The Crux of the Matter” weekly radio show on the Sirius XM 129 Catholic Channel with three of Crux’s head honchos: editor and veteran Vatican analyst John Allen, managing editor and longtime Vatican Radio staffer Charles Collins (he must do the real work at Crux to let Allen do his Vaticanalysis), and senior contributor and Frankenpope-sycophant biographer Austen Ivereigh (as “senior” he must be the oldest of the group, although with the other two having “veteran” and “longtime” labels, they must all be oldtimers)
… Allen floated the idea that Pope Francis at some point over the summer may replace German Cardinal Gerhard Müller as Prefect of the Congregation for the Doctrine of the Faith.
Granted, Müller is only 69, so there’s no immediate reason why a successor has to be named. However, he was first appointed to his position by Benedict XVI in 2012, so by normal Vatican standards the usual five-year term as head of a department will be up, and anyone with eyes can see that Francis and Müller aren’t exactly in sync on some issues, including the implications of the pope’s document Amoris Laetitia for the contentious issue of Communion for divorced and civilly remarried Catholics.
If Francis wanted to be completely transparent, he’d probably name Argentine Archbishop Víctor Manuel “Tucho” Fernández as Müller’s replacement, since it’s fairly obvious that Fernández is the figure Francis relies on when he wants a theological assessment of something. However, there’s good reason to believe that Francis likes Fernández where he is, free of the labyrinth of the Vatican, and is unlikely to bring him to Rome.
Assuming that’s the case, who might Francis tap to take over from Müller?
Allen floated the counter-intuitive idea that one candidate could be Cardinal Sean O’Malley of Boston, widely seen as the Church’s leading reformer on clerical sexual abuse. Given that the doctrinal congregation also has primary responsibility for handling accusations of abuse against clergy, if Francis truly wanted to make a statement about change, there’s no better way than naming O’Malley … and since he already has someone else to provide doctrinal counsel, he wouldn’t need O’Malley for that.
For the record, no one else found that an especially persuasive scenario.
Of course, we have no idea what Francis will actually do. What we do know, however, is that he is an activist pope who finds himself with some time on his hands this summer, so the best advice probably is simply this: Stay tuned!