I've been working with a lot of clients lately that use the "Three Horizons" growth framework explained first (?) in The Alchemy of Growth, a book by a set of McKinsey consultants from the late 1990s. Here is McKinsey's enduring ideas explanation of the framework.
For the most part, I'm seeing people misuse this framework. Rather than managing the horizons concurrently, people are using the horizons as a taxonomy for organizing ideas (sounds like a "horizon three idea") rather than to assess relative activity ("do we have a steady stream of S-curves stacked up on the horizon?"). In a sense, they are using the framework to do exactly what it's meant to prevent.
Horizon Three innovation is here today. You just aren't working on it.