Here's what I think of the current API:

• The current list of hooks is a bit overwhelming. Do we actually need canActivate and canDeactivate? It seems activate and deactivate can already handle most use cases with transition.abort() and transition.redirect().
• The data hook name is not that self-explanatory.
• The way we determine the async-ness of these hooks is convoluted. Sync, Promises, callbacks... we should try to simplify it.

Idea

Some potential breaking changes for 0.8.0:

• Remove canActivate and canDeactivate.
• (Maybe?) Remove canReuse. The same component is always reusable. Handle route change in onChange.
• Rename hooks, now we have just 3 of them:
  • onEnter: what activate used to be.
  • onLeave: what deactivate used to be.
  • onChange: what data used to be. The new name better explains when it is called (on every route change when the current component is active)
• In addition: allow specifying onEnter and onLeave in the route config as well.
• Open to suggestion: how do we simplify hook async-ness?