In classic workflow, we have Record Status change among many other events those can be used to trigger the workflow.
Previously we thought classic workflows will be history by now with introductions of Cloud Flows. Though cloud flows are pretty powerful in terms of collection of connectors we can use etc. Anyway, still its not helping the developers in many way;
- Connection strings are still a complete mess that easily jeopardies a deployment
- When logic of Cloud Flow is growing, the illustration becomes very big and not easy to have a one view even via a big monitor.
As per this writing, classic workflows still running in most of the implementations of the world and no sign of getting replaced that easily for a long time.