I can't see anywhere else on the forum that this has already been discussed so pardon me if this is old news.
I have just come off the phone to Virgin Atlantic after discovering by chance that they have changed my flight. I was booked to travel from Manchester to Las Vegas on 7th November, returning on 14th November and went into my booking online to check if the seating plan had been released. It was only then that I noticed the flight was showing as departing and returning to Gatwick.
I called the customer service team and was told that the Manchester flights have all been cancelled between November and March.
I thought it was nice of Virgin to let me know.