As an example, how does a Heathrow-San Francisco or Heathrow-Dubai route really benefit Skyteam, when Pairis-CDG and Amsterdam both already have excellent local feed from all over Europe as well as plentiful long haul flights ?
Such routes would benefit Skyteam in the London market. I doubt many business travellers at least are going to be doing LHR-CDG-DXB or LHR-CDG-SFO for example when there are plenty of non-stop options available. If Skyteam, or DL/AF have decided they want to have a larger share of the London market, they need to offer a wider range of non-stop destinations covering key global cities, Skyteam hub or not
What VS brings is a presence in most major long haul markets from London. Being able to offer non-stop LON-Tokyo, LON-Hong Kong, LON-Los Angeles can only help Skyteam in the London market, and also in the foreign markets concerned as well