In regards to the Adobe side of things going away. I believe Kobo partnered with the idpf because of this, as I think they pretty much stopped doing anything for ePub3.
Kobo is certainly listed on the membership list
here.
In addition Kobo is a member of
Readium too. In fact the EPUB Lightweight Content Protection initial spec proposal is written by a certain Mr Jim Dovey, who is the Digital Content Format Evangelist for Kobo.