The difficulty for the 'No' campaign is one of 'credible threats'....it's simple game theory. The No campaign can say all it wants, but the reality is, if Scotland did vote Yes, they would have to negotiate, and there would be no incentive for them to stick to what they're saying right now.
The US and Russia understood this well - mutually assured destruction...the only way to make a threat credible is if it's impossible to back down.
The government minister who said there would have to be a currency union with an independent Scotland is "totally, plainly, utterly and flatly wrong", Nick Clegg has said. The deputy prime minister said he did not know whether the anonymous minister who spoke to the Guardian was a Liberal Democrat, but the comments should not be invoked by Scotland's first minister, Alex Salmond, to give voters false hope. A currency union was not going to happen and was "not available to Alex Salmond", he told reporters at his monthly press conference.