There are rumours of Dominic Cummings leaving by Christmas 2020.

I am fairly sure, though not 100%, that several years ago there was talk of him staying until Brexit was through. If so, disappearing from the scene just before the end of transition would fit precisely with that plan. There have, however, been a long series of 'Cummings is about to go' stories every six months or so since the 2016 vote. He was leaving for health reasons, then only staying to see Boris become PM, then Boris get elected, and so on, so this could well be another of those. On the other hand he is a handy recipient for the Cabinet to blame for any of the decisions over the last year that did not work out as they wanted.

we will see. With luck, if he goes, the disruptive plans he has initiated for pretty much all governmental bodies will go with him.