I believe
@SlyFlourish has said he contributed some information about building encounters and monsters to WotC as well as to Kobold Press. I can see that showing up in either the DMG or Monster Manual equally.
I am looking forward to at least modestly improved magic item creation rules (but please don't toss out the 2014 tables on magic item properties, which were great) and some simple spell creation guidelines along the lines of the 3E DMG ("compare to existing spells, and these types of damage are better than those, so drop them a damage die when you make a spell of that type").
Mostly, I'm just counting on much better organization, which it sounds like WotC has gotten the message on.