High level goals:

• Tracing on ScalaJS (including enhanced exceptions)
• Fiber dumps on JVM (and possibly also NodeJS), including both live and suspended fibers
• Greatly improved fairness in the JVM scheduler, particularly in cases where a lot of child fibers are being created (think: parTraverse)
• JMX metrics for the work stealing pool
• First-class support for mocking the runtime, allowing deterministic tests against time and even future support for adversarial scheduling (think: scalacheck for race conditions)