I just wonder: with Java 8, and the possibility to add implementation in interfaces (a bit like Scala traits), will it be possible to implement the cake pattern, like we can
Ignoring the new functionality in Java 8 you can in theory do the Cake Pattern in Java 5 and above using compile time AspectJ ITDs.
AspectJ DTO's allow you to make Mixins. The only annoying thing is that you will have to make two artifacts: the aspect (ITD) and the interface. However ITDs allow you to do some crazy stuff like add annotations to classes that implement an interface.