Are you proposing that Java 8 closure syntax is the solution to deeply nested callback code? Hopefully not---because that doesn't really follow IMO. A proper solution for concurrency is to use the Actor model or something similar.
It's a solution for tons of boilerplate code which appears when trying to do patterns. Compare for example Reactive Extensions (which are pretty popular in Android community for management of concurrency) and just how much more verbose is Java 6 code with it's piles of anonymous classes vs. lambdas of Java 8 or Scala. Even though IntelliJ IDEA can hide that boilerplate pretty well, it's still tons of needles code you have to pollute your codebase when you're implementing those modern patterns.
In short, what I'm saying is, that at the current state of Android, implementing Java 8 features would bring simillar benefits than switching to a whole other language without having to rewrite whole runtime and most of the operating system.
