As someone who is also booked on the Greece and Croatia cruise, this had been my hope. But based on this: https://www.seatrade-cruise.com/ship-operations/when-brilliant-lady-joining-virgin-voyages-it-will-be-while it doesn't seem like Brilliant will be doing anything for a while.
At this point I'm working under the assumption that my cruise will not be going ahead as planned and I'm booking (fully refundable) hotels instead. I'm slightly frustrated with the "wait and see" approach, but VV isn't the only line who is doing that.