Aside from very much needed java 8 support in 2.12, Scala, IMO, has little need for more bells and whistles. Making a sound and coherent foundation instead would be much appreciated.
Will it break a lot of codebases? Yes, it will.
Will it break a lot of codebases? Yes, it will.
There's a tradeoff between breakage and improvement, but I'd like not to wait 10 years before I can use dotty (like python 2 to python 3). We can always have another dotty in 5 years time for another round of rationalisation/simplification.