I'm not sure about universal cannibalism. It's well documented that people in Ayrshire would take to it like ducks to water, since it's already in their ancestry. However the douce ladies of Edinburgh might be slightly less easy to persuade. Perhaps an expertly prepared béarnaise would tempt them. The teuchters are all sheepshaggers anyway, so a bit of rape, pillage and cannibalism would be a natural step in their evolution.It's pretty much known by everyone that Scotland would become a failed state if devolution ever occurs. I'm not sure about the cannibalism, but it's a strong possibility once the regional government collapses and the periphery political actors are left to their own devices. Just as likely is the possibility of the people going back to piracy as a means of livelihood. A model of a future Scotland can be seen in current day Somalia. It would probably be in the best interests of the EU and the world to stop the creation of a failed Scottish state.
As to piracy, the lowlanders would be rubbish at it, except perhaps all the rich bastards who have yachts at Largs and Kip.