milo
Jack L. Jones
First I don't think May will have the strength for a big reshuffle. She's probably quite in danger of an internal coup after the election, so will need to appease her big beasts (including Johnson)
And second Davis has done a year's prep for Brexit and is specially positioned as he and Michel Barnier are old drinking buddies from the 90s (they were Europe ministers for UK and France at the same time). It would be foolish to throw away those those advantages
If May doesn't have the strength to hold a reshuffle immediately after the election, she won't have the strength to see Brexit through.
I think that she will be fine in the short term though. She looks like she is on track to get a 40-50 seat majority which will buy her a few years and allow her to pick the cabinet that she wants.
The rumour seems reasonably well sourced and there have been rumours of senior cabinet members being moved throughout the campaign.
The problem that she has is that none of the three Brexiteers are particularly strong on detail and we are about to enter an incredibly detailed and complex set of negotiations.
Moving Davis to the Foreign Office where he can charm other countries plays to his strengths. Gummer is meant to be bright and good on detail and has been a member of the No 10 Brexit committee, who are running the show, since last summer. Johnson is meant to have resisted moves to make him party chairman but it does feel like it is the natural role for him.