Delta can negotiate what they wish with their pilot groups, but it seems to me that this restriction of the airline of one country on an airline of the other country is not permissible under the Open Skies agreement.
Yes, it's also not a good idea to make oneself a hostage to fortune, in the sense of tieing DL's rate of growth to that of VS's.
EI-BUD is correct about USA consolidation and Europe has a lot further to go. Sadly, VS is a spent force and will (now) remain a niche player. The failure of Branson and Bishop to do a deal in the 1990s (whose ever fault it was, let's assume it was 50/50) was the point at which VS could have become a real player but it failed and one carrier is gone and the other a shadow.
This only serves to emphasise the importance of consolidation.
(I've never worked for VS but am a satisfied customer of many years)
Indeed, a point made in post 788.
yes BD and a limited longhaul connecting network was going to be a rip roaring success.... BA would have had them for breakfast, dirty tricks or otherwise.
As independent entities possibly, but with BD as part of the Star Alliance, with other Star Alliance longhaul and shorthaul feed, a more comprehensive BD/VS collaboration may well have worked well at LHR.
Not big enough to make BA/One World lose any sleep, perhaps, but enough to provide viable competition and choice to pax.
But we'll never know for sure.