As already mentioned, the upgrade path for large apps is not quite as simple as the line implies. Ignoring that, this concept of backwards compatibility above

As already mentioned, the upgrade path for large apps is not quite as simple as the line implies. Ignoring that, this concept of backwards compatibility above all things is so strange to me. How modern browsers work has changed fairly dramatically over the last several years. Not to mention a major, major overhaul of ECMAScript. And yet, every. single. time. we have something that mentions backwards compatibility being straight-forward, the top comment is always about how re-writing frameworks are bad. I don't have a problem with the way the Angular team are doing things. Angular 1.x will be supported for a long, long time. And even though this hasn't been announced, I expect the 1.x and 2.0 branch to gradually merge, requiring minor changes to code at each minor version increase. So effectively, Angular 1.4 -> 2.0 is no different than Ember 1.0 -> 2.0 with the caveat that 2.0 was planned in advance so all of the minor version changes will lead to 2.0, rather than 2.0 being the outcome of minor changes in 1.x.