2.12 doesn't include any (non-gated) changes though, so you can keep the same codebase and cross-build for 2.12 (for performance) and 2.11. So we're talking what, at least 3 years ("Aida", either 2.13 or 3.0) before Java 8 becomes a blocker for source-level features, at which point I imagine Android will have an answer.