I'll try to cover couple of them. Hopefully, others can fill in:
- funs have an extra dot in the name: not fixed because that will lead to inconsistency [1]
- send operator: removed earlier this year and the operator is reincarnated as comprehension operator (comprehension being more ubiquitous [2]); although, the proposed syntax wasn't adopted
Not sure about funs and def. It appears that not much was discussed about versions in source file and docstrings inside function definition (module doc is already inside); the later one can be dismissed being a common bikeshed in PL design.
So, yeah, most of the proposals couldn't make it because of complications.
[1] https://groups.google.com/d/topic/elixir-lang-core/_kEBXO0NR...