Get 20 787/A350s and you are flying! Literally!
I wouldn't bet on it. By the time these aircraft are rolling into LHR they may just have three runways to play with.... Virgin Atlantic's presence outside Heathrow does look restricted to leisure routes. I guess they might try LAS or similar but they have a MASSIVE investment in gaining and retaining premium traffic. Look at the money going into facilities at Terminal 3 Heathrow. Last time I looked they were even refusing to pay for airbridges at Manchester. Don't set yourself up for a fall hoping for a based fleet serving New York / Los Angeles etc.
You know where that amount of capital expenditure is going to start paying its way and realistically it's NOT Manchester.