Discussion is happening here. There are trade-offs, but we do believe there are identifiable benefits.
All of it? 
There’s so much missing testing that pretty much any testing is welcome. I haven’t had time to put thought into what testing in particular we want, but I think with the work being done on Autoware.Auto, for Autoware.AI I’m happy with unit testing and system integration tests.
We are probably going to have unofficial support for Melodic and Ubuntu 18.04 in 1.11. As I recall there are just some issues with Docker remaining, I’m not sure if those have been worked out yet. So having it officially supported in 1.12 is doable.
This is already on my list to do for 1.12 as part of cleaning up the repository and issues. I’m going to pare it way way back in the first couple of weeks and then any remainders we will sort out over a longer period. The ideal is that we just have the master branch and a bunch of version tags; it remains to be seen how close we can get to that.
The creators of unmerged branches are going to get a message asking them to sort out their branches. For ones where the person has vanished, we can try to find someone else to take over updating and PRing that work.