I'm not sure we could do a "full" integration for facades inside the Launcher, since if the code is in there - it would have to reference classes and libs for the engine without depending on the engine and its libs ?
I see the launcher as the ultimate in convenience, but staying optional - you should be able to do everything from inside the game if you really want, including modules and such (with the caveat that you might have to then restart or do other stuff that needs activities outside the game). But if at all possible - use the launcher.
As such I think we should have a couple elements that work on both sides, for instance a module tracker utility that can do lookups and pull down modules. That would be a separate lib project, used by both the launcher and engine.
Facades the concept is still up for definition though. Originally it came with the example of Android support, which is a much more "proper" - that's not something you'd bundle with the "normal" version of the game, it is a very different wrapper around the same engine.
Launcher should be able to pick facade when multiple sensible choices exist, but I don't think the launcher should itself provide facades. Not that it couldn't actually download them separately, since they do exist in other repos/jars.