May happen in the short term. Then we can source stuff from Australia, New Zealand, South America and Canada. We will get it cheaper due to prices of food stuffs in the EU area being kept artificially high to keep the French farmers happy
To ship a container far exceeds both the cost and carbon of road haulage. A container has to get to and from port as well, plus they hold considerably less. Also factor in that every pallet shipped to or from your mentioned places will need to be on heat treated pallets. Essentially they need to be heated to kill bugs in the wood, adding significant time, cost and carbon.
Food prices are going up, thats not even a debate unfortunately. Deal or no deal, they are going up.