Oh Amiens would benefit, as would the Pas de Calais. But in the scheme of things, not a great deal.
Re LGV Nord, I’ve often wondered how busy it is. At the busiest times it has two trains an hour to each of London, Brussels, Lille (alternating between Lille Europe with extensions to Calais / Boulougne, and a direct Lille Flanders service), plus 1 train an hour to Arras which splits to Dunquerke and Valenciennes. Then occasionally services from Lille (or further north) via Massy / CDG to other parts of France. Perhaps 8 an hour in total, are there any more? Doesn’t seem that full to me.
Re LGV Nord, I’ve often wondered how busy it is. At the busiest times it has two trains an hour to each of London, Brussels, Lille (alternating between Lille Europe with extensions to Calais / Boulougne, and a direct Lille Flanders service), plus 1 train an hour to Arras which splits to Dunquerke and Valenciennes. Then occasionally services from Lille (or further north) via Massy / CDG to other parts of France. Perhaps 8 an hour in total, are there any more? Doesn’t seem that full to me.