So this post is about a year old. Looking at the .NET blog, I don't see any direct follow-ups. How did this pan out?
If you think MS ever would "pull out" of mobile and be satisfied with "being a guest in someone else house", your insane :)
Fewer models, to be exact. In contrast to their old strategy of saturating the low end with multitudes of confusingly numbered Lumias they're consolidating into three distinct lines. Presumably they want to have volume!