We started working on a redesign of the standard collections in the following repository:
There is also a corresponding gitter room:
The goals of the redesign are to fix most of the issues of the current collections (e.g. the complexity of CanBuildFrom, immutable operators on mutable collections, lazy vs strict collections, huge class hierarchy, etc.) while keeping a similar user facing API.
The redesign is based on a strawman written by Martin Odersky and is still being polished.
We will keep you informed of our progress and decisions in this thread. Feel free to discuss and comment!