We've had this feature in beta for a long time now. Thanks to everyone who has helped us test drive A/B testing in Workflows.
Whilst functional in its current state we've had a lot of feedback around the way we currently record conversions and how we handle the "control" case.
Whilst this feature is 95% there and we have released some bug fixes for it recently, we don't yet feel comfortable releasing it to all customers until its working perfectly. We have some ideas as to how we might revisit this entirely.
We won't be working to complete this in the coming sprint but are marking it as 'under review' as we are working on our plan for finishing it during a future sprint.