We don’t expect to change the API of legacy features so you can start migrating your projects if you want. However, keep in mind this is still a beta version. This means that some problems might arise (for example: gh#1182) and you would need to spend some time fixing them or reporting issues.
Templates will be updated when the final version or RC is released. As for the TypeScript support, we provided this .d.ts file some time ago. It was made for 1.3.0 so we would need to update it as well for the final release.