I don't know if others saw my post on another thread but this was a webpage about the V6 on offer due to the price rise. It actually mentioned BT Sport in 4k. The virgin team on the community forums said it was a mistake and was removed but it doesn't look like a mistake to me and could be a leak that it is coming soon.
It also mentions a new app called Virgin TV Go which will finally allow streaming over 3G or 4G.