NG Mobile OS
Javascript: react-native or nativescript
Since app logic is event-based, that we need a lot of request and async stuff, plus a xml/html view + style management :
For me the best native replacement for java would be javascript.
It would only take one require of an "android" module to access all it's api.
The models and logic would be directly imported from web apps and could lead to a webview port easily on iOS.
There are a lot of steps taken in that direction : Cross-Platform Native Development with Javascript React Native | A framework for building native apps using React
chrome
They might gradually phase Android out in favour of their Chrome platform.
Google's investing a lot on Chrome - not just the browser but Chromecast, Chromebooks, Chrome Web Store, etc. They're also removing Android branding from a few places like their Store. Chrome browser is becoming a robust developing environment which they have total control over - rendering engine, networking, service layer, dev tools, etc. Google's even investing in public libraries such as AngularJS for web development, perhaps with the intention of raising momentum of web app developers, community. I can totally see them directing AngularJS and their evangelists towards 'AngularJS for Chrome', adding a Chrome UI module or something that respects their Chrome UI guidelines and plugs into Chrome Dev Tools.
In which case, the answer is JavaScript. (Or some of their semi toy languages like Dart)
chrome os run android app
据外媒报道，看起来谷歌很快就要打破Chrome OS跟Android之间的屏障了，也就是说，Chrome OS将能登录从Google Play Store上下载下来的Android软件。日前，一位Reddit用户在运行Chrome OS v51的Chromebook中发现了这条线索。据他披露，系统设置菜单中有一个写着"Enable Android apps to run on your Chromebook让你的Chromebook能运行Android应用"的复选框。
不过没过多久这个选择就不见了，但Chrome OS源代码似乎预示了这个可能性。
目前出现这项功能提示只发生在Developer Channel中，并且据开发者透露，当他们启动这项功能后系统仅提供了一个教程，并且很快就会自动关闭。也许这是谷歌正在为下个月的I/O大会而正在准备的一项功能。
2014年，谷歌首次让一批Android软件（其中包括了Vive、Evernote、Duolingo）在Chrome OS上运行。次年4月，谷歌发布ARC(App Runtime for Chrome) Welder应用以此扩大支持范围。
倘若谷歌此番真的能推出这项功能，想必其系统一定能为更多的用户所欢迎