Also I don't have any issue with Java as I do like the language and use it since JDK 1.0.1.
My issue is with Android Java, a forked version of Java with cherry picked features of Java 6, 7 and now 8, just because Google didn't want to pay Sun.
A version that will be even harder to write portable code when Java 9 and 10 come out.
I believe Google is running out of solutions to further optimize Android because they keep running into self inflicted Java roadblocks. If Fuchsia is any indication of their future efforts their next major overhaul will support multiple first class languages.
As for Fuchsia and Brillo, it remains to be seen if they will ever be productified.
Also I don't believe that Dart is a better option than Java in regards to performance.