WebAssembly Migration Guide
Given the momentum of cross-browser WebAssembly support, we plan to focus our native code efforts on WebAssembly going forward and plan to remove support for PNaCl in Q2 2019 (except for Chrome Apps). We believe that the vibrant ecosystem around WebAssembly makes it a better fit for new and existing high-performance web apps and that usage of PNaCl is sufficiently low to warrant deprecation.
WebAssembly 上位官宣
为了给 WebAssembly 添把火儿，我们打算把 Native 代码的能里放到 WebAssembly 上。从 2019年 Q2 开始，不再支持 PNaCl（Chrome Apps 除外）。
我们认为 WebAssembly 活跃的生态能够胜任现有的和以后的 web 应用的高性能需求，所以 PNaCl 是时候滚蛋了。（duxing 翻译）
摘自：https://developer.chrome.com/native-client/migration
