Nothing from the company to pilots about the change.
I've seen the documentation and it's a clear instruction. It's designed to standardise all the separate Virgin ops under one callsign. Officially VOZ never had a recognised callsign, "VIRGIN" was simply taken up by crew/atc instead of "VOZZ" I guess (and DEEJAY before it). If I'm correct the ICAO designators stay the same (PBN etc) it's simply for phraseology. I'll find out when it comes in to effect tomorrow unless someone beats me to it.