Virgins don’t survive on their own. That’s the lesson drawn from Virgin Atlantic’s partial sale to Delta, Virgin America’s all-out sale to Alaska and a much earlier transaction between Belgium’s Virgin Express and what today is Brussels Airlines. The most striking example of all, however, is the case of Virgin Australia. Once independent, strong and profitable, the airline that started life as Virgin Blue ultimately fell victim to its own ambition, leading to perennial capital shortages. These shortages, alas, led its CEO John Borghetti to sell pieces of Virgin to not one foreign airline, nor two nor three nor four,…