Never say never, but I would be amazed if VS buy BD mainline.
SQ have wanted out of VS for years so they are not going to contribute any capital.
Virgin Group rarely acquire businesses/merge by offering cash which is what LH will want to dispose of BD. Virgin contribute assets in return for shares or licence their brand. And, most importantly, I doubt Virgin has the financial muscle to absorb the losses and turn BD around.
An IAG deal is still a possibility. The 6 slot pair deal has probably been negotiated for months before the recent announcement by LH that BD could be sold.