When it will be? It’s when 2/3 of android users use OS above Jelly Bean(4.1) and 2/3 of andriod users use browsers other than the Stock browser.
The thing about OS version is obvious, but the Android Stock browser? Benchmark shows that the Stock browser is better than the Chrome browser..
However, Android Stock browser could vary by phone maker’s customization and it’s not easy to update. Maybe that could be the point.