The market would take care of that. Now my question is why would any Briton with even a basic understanding of economics want to adopt the Canadian model (which works for Canada only because we don't depend as much on the EU as the UK does) or fall back to WTO rules (which the UK could survive but at a great price in both the short and long terms essentially eliminating the UK as an economic world power over time).
In all honesty, I can see only two reasonable ways out for the UK: stay in the EU or adopt unilateral free trade. Unilateral free trade would inevitably hurt in the short-to-medium term since it would require an adjustment period and it's debatable which of the two options would benefit the UK the most in the long term (both being more or less tied for their potential benefits to the UK). Any other option would hurt the UK in both the short and long term.
With that, if Brexiteers really want to make a hard break with the EU, it might be time for them to be brutally honest with the British people that to make a successful hard Brexit would mean unilaterally dropping all tariffs and subsidies, that it would inevitably hurt the UK economy at least in the short-to-medium term, and that economists are divided as to whether remaining in the EU or unilateral free trade would benefit the UK the most but that either way, even if unilateral free trade would benefit them more, that they'll have to go through much short-to-medium-term pain for the small long-term advantage.
If they are brutally honest with the British people on this, maybe, just maybe, the British people might choose short-to-medium-term pain for unilateral free trade as a potentially, debatably more beneficial long-term arrangement for the UK. But at least they'd now be making an informed decision.
