Anyone But England
If by some freakishly unlikely chance Scotland has a team in a World competiton then the national team will be feverishly supported right up till they are eliminated... then the Anyone But England fallback position will kick in.
Teams all round the World look forward to being drawn against England since sales of their uniforms/hats/jerseys invariably skyrocket in Scotland. Example: England's 2006 World Cup 1st round opponents Trinidad and Tobago sold more merchandise in Scotland than was sold in Trinidad and Tobago.
A similar phenomenon exists whereby the England fan chooses his allegiance to be any team playing against Germany, France or Argentina. Teams playing against Scotland in any World-class event - apart from Elephant Polo - are such a rarity that insufficient data exists to formulate a theorem although if no support is forthcoming, I doubt the Scots will spend 6 weeks whynging about it on national TV.
It's only when Germany, France or Argentina are playing against each other that there is a problem. In this instance, the England fan will follow the Germans against the French and Argentinians, or the French against the Argentinians.
Does not apply to Elephant Polo (since we're great at it)... or curling.