The silhouette they showed off of the guy holding a banner is probably from the command squad, and he was in MkIII, but he was also pretty clearly one of the existing MkIII poses with new universal arms -- the default MkIII arms on the sprue have sort of flanged elbow armor, but the silhouette didn't, so the arm holding the banner seems to be the new universal arm design visible on the plastic heavy weapon upgrades and the resin despoiler upgrade kit. In short, the command squad'll probably be one or two of the new MkIII sprues plus a universal command upgrade sprue designed to be used with all the new armor marks.
I suppose we will see eventually. If they are mk III like you say then I'll just go with my original plan and kitbash my own command squad. MK III will be great for my next project though. 👍