My rough idea for a roadmap is as follows:

Release a 8.x-1.0 alpha

Garland is pretty much presentable at the moment. I'd like to get this fixed before an alpha release, but it's not vital:

* #2282365: convert fieldset styling to details

After that, keep up with core development and fix any styling issues that crop up.

Release a stable 8.x-1.0

Depends on when 8.0 is released ;)

Start a 8.x-2.x branch

The two big things I envision for this would be:

* Replace the PNG background files with CSS gradients. I've started playing around with this and it looks promising. It would probably need the underlying HTML structure of the header and breadcrumb area to be changed, as we would need the DIV edges to line up with the borders, rather than with the far end of the dropshadows.
* Make Garland responsive

Any thoughts?