Hello !
To my knowledge the features of the next Ubuntu MATE release will mainly be Mate 1.22, the adoption of Evolution in place of Thunderbird as default mail program, and Gnome MPV (newly named as "celluloid") in place of VLC.
Do you know other changes and progress to come ?
There has been a new brisk menu release, which may have a new dash mode or a revised one?, I imagine that's going to be in 19.10
So far, that is all we know.
You can try daily Ubuntu MATE 19.10 builds in a VM (takes 3 clicks using gnome-boxes) if you want to check the new stuff.
I tried yesterday's build and VLC was still in it.
Evolution was there and Brisk Menu 0.6 as well.
Just a quick question did you try the brisk menu out, what's the big changes?, I may try it live as my current hardware can't run vm's worth anything at all
Haven't played much with it.
Add a new "dash" style menu.
Fix super key global bindings on Compiz.
Unset Lock key masks when closing menu.
Fix key-binder from swallowing Super+Mouse events.
Update API for MATE Desktop 1.22.
Make favourites appear first.
Fix categories list so scrollbar is not always shown.Ok I had seen the changelog but haven't seen anything besides that, I'll just have to try it out 
so I'm not sure what has changed as far as the new dash style menu, cause when I tried it out it seemed the same as before other than favorites being first which is an improvements, also the indicator improvements make UM feel much more consistent and modern imo, and there is all the improvements of MATE 1.22 which are nice, however I thought MATE 1.22 would recognize all Gtk themes even the Gnome 3 style ones with the big fat title bars, but when I tried some that did not appear to be the case, though marco did throw some errors, clearly still a WIP but definitely some improvements imo