hi all!
let me explain my position, and sorry for bad english.
I have system with kde4.
in this system i have 4 activities and 6 VDs.
activities are Video, Audio, Draw, Other
VDs are Main, Mixers, Effects, Visualisations, Configuration, Other.
For all of thees i have personal widgets and desktop settings.
Moving to KDE5 i'v losted most of this settings. now each VD have same all of widgets and settings with other.
i think it's bad idea to remove usefull feature. What was reason for it?
Better will be make personal VDs for each activity (3 VDs for one activity, five VDs for other one, etc.. with personal naming).
Now i see only degradation of KDE plasma.
Will it be posible in next releas to backward VDs configurations? or i can downgrade or use other dektops as well, do i?

Per the comments on the bug report referenced earlier, It sounds like the feature may be coming back eventually (but it requires a significant rewrite of a lot of code related to VDs and/or Activities to be able to handle this better).

An idea for handling the case you describe could be to create separate Activities for each Activity+VD in your previous set up (possibly excluding unnecessary pairings, and/or merging pairings which are really just the same activity or always have the same set of widgets).

(edit: after reviewing the bug report some more it seems the devs may still be working on it)

If you just want different wallpapers for each desktop in Plasma 5, my extension (KSmoothDock) supports it:
https://store.kde.org/p/1081169/