Regarding the new direction of the Grot faction, i wouldn't even need for GW to give skaven the full new release treatment to be happy. I would be very happy with a complete consolidation tome and a couple new units and spells. New units, endless spells or some kind of gnarlmaw mechanic that allows for board mobility, like a gnawhole or spawn pit to deploy your units with. But i don't need a full release like nighthaunt or grots got.
Units i would like to see would be something along the lines of:
New eshin models. Some kind of lesser verminlord daemons. Bigger warmachines for skryre, like a big drill or the twin tail comet machine from total war 2. Maybe some new plagued pestilens rat ogres or explosive bloated rats. I would also like to see something completely new like the rumored skybound skaven with flying machines.
Now that i think of it, i want lots of new models! I wouldn't mind waiting either.