Moving forward, we plan to do a few major things straight away:
1. Remove most or all of the deprecated functions.
2. Switch the default terrain engine over the REX. The MP terrain engine will remain, but we don't anticipate any further development for it aside from keeping it compiling against the OSG master.
3. Deprecate the osgEarthQt node kit. It will remain in the repo for now, but will likely go away in the next version. In the meantime it will only work with OSG 3.4.x since newer OSG has removed its osgQt namespace. We are not going to update it to work with external osgQt. Feel free to copy and use the code in your own applications.
Future plans will be forthcoming. Suggestions, feature requests, etc. are always welcome :) Thanks to everyone for the testing and support!