If VS were to take any of their A380 options they would most certainly be best suited on the LHR - JFK route. I could see possibly LHR - LAX/SFO working and maybe MAN - LAS a couple of times a week.
But, like other posters have commented, it is unlikely VS will get any A380s and if they do, I see it being for the status and branding. But that's just my opinion, and I have no scientific backing to that latter postulation.