Rob Wormald, developer and Angular core team member at Google. He told InfoWorld that Angular 4 will be released in March 2017.
Angular 4 will have better tooling and will generate less code; Google also is promising a new major version twice a year.
Key features of Angular 2,
1. Angular 2 is faster and easier than Angular 1.
2. Angular 2 is mainly focused on mobile apps.
3. It supports latest the version of browsers and also supports old browsers including android 4.1+.
4. It is a cross platform framework.
5. Code structure is very simplified than the previous version of Angular.
Why Angular 2?
1. The Angular 2 has better performance.
2. The Angular 2 has more powerful template system.
3. The Angular 2 provide simpler APIs, lazy loading and easier to application debugging.
4. The Angular 2 much more testable.
5. The Angular 2 provides to nested level components.
6. The Angular 2 execute run more than two programs at the same time.
For more details about Angular 4,