I was thinking about LINQ, specifically. Ok, LINQ is too much (and too specific), I wouldn't like something like that in D, but something similar...
my point is that operator overloading helps only i a very few cases - and even then (see syntaxhighliing in boost::spirit based parsers) it does not realy help
but it think (again, except the compiler bugs) D is be able to do something like LINQ (as an example) with mixins (or ast-macros) without the need of extending the language itselfe - only the parsing on compiletime thing needs to be easier - but any solution(s) in this part of D will also help all other generic library developers