Hi David,
Totara LMS is a custom distribution of Moodle, not a plugin. They are developing a mobile app based on MoodleMobile.
The idea is join efforts so MoodleMobile can benefit from new features added in the Totara app that are not specific for Totara LMS
Regarding the future of Moodle Mobile, I can assure you that we have a long roadmap for MoodleMobile app, I was talking in person with Martin Dougiamas last week, also here is the presentation I did with Martin Dougiamas a few days ago in the MoodleMoot Spain. Things like responsive themes are described:
Regards