If it happens - and I think it's massively unlikely - it will be after rationing and food shortages caused by Brexit.
It was an example of extreme-scenario planning. Government's-in-waiting should do that.
The real scandal is that our present government has a staff turnover of 20-25% at its Department for Exiting Brexit, where planning for a real set of scenarios is going at a snail's pace. Apparently, Civil Servants in the Dept. are spending time planning for how to cover their backs for a post-Brexit Chilcot-style enquiry (into why they didn't prevent an economic disaster).
I'd say, spend less time worrying about hyper-imaginary scenarios.