Not going to testify until after an official FBI investigation? That changes the dynamic as this is now a trap for them. Damned if they do and damned if they don't. I don't think they are going to stick their necks out unless there is compelling evidence to become involve in a political dispute.
So the accuser isn't going to testify, she looks bad now as her changing her mind and insisting something that isn't likely to happen. Well, that's a fork in her IMO. Whether her involvement prevents Kavanaugh from getting in remains to be seen but this is even more a cluster.
What needs to happen are rules that cannot be waved, such as a minimum time to evaluate candidates and deadlines for evidence and documentation as well as the kinds of materials that must be provided.