I do expect to see the dungeon masters guide changed substantially. We've heard tales that the product was rushed and designed alongside the players handbook with priority on the latter. In addition it is filled with much fewer rules that would cause chaos to change; It doesn't matter if they change encounter rules to match modern guidance or if magic items aren't right in the middle of if the guidance on setting building changes.

The PHB revision has written itself into a corner by their design goals clearly changing during production to keep the 2014 edition totally compatible instead of adaptable, the other products already are not beholden to that ethos because there is less comparability overall.

That was the original promise before the playtests, No new edition.
They are afraid of splitting the fanbase with a new edition, so anything too different will be scrapped.

I backed MCDM's Flee, Mortals. While they can't use Wizards monsters so there's a lot of change in lore and names, it's so good that I don't think I'll ever need a Wizards updated MM.

Fingers crossed that the changes to the MM and the DMG are more substantial.

To be honest if its gonna take really any effort at all to learn a new edition, myself (and I think a lot of other DMs) are going to look very seriously at other D&D-alike games.

Shadow of the Weird Wizard, the new MCDM RPG, Shadowdark, Pathfinder 2e, the new Kobold Press RPG (is it still called Black Flag?), etc etc.

There has never been a better time to look at other tabletop RPGs as it seems for once WotC have a load of real competition.