Well, you probably can build ifdef-style things with inline, but it won’t be based on simply removing part of the sourcecode without syntax checks 
A nicer use case (which sadly will only work when 3.0.2 is released) is using it to check literals for opaque types, e.g. to have an int type with a limited range, where creating one from a compiletime constant doesn’t need to be checked at runtime. See "Given" style Implicit Conversion with inline function for a discussion on this.