https://en.wikipedia.org/wiki/Trade_bloc..._blocs.png
Interesting link, if you look at it, Americas, India, Soviet Union and so on all have there own trading blocks seperate from one another, including a couple of European free trade.
Presumable now, the UK can trade with any of these without restrictions from the rest of Europe.
From the above link:
Advantages
There are five major advantages of trade bloc agreements: foreign direct investment, economies of scale, competition, trade effects, and market efficiency.
Foreign Direct Investment: An increase in foreign direct investment results from trade blocs and benefits the economies of participating nations. Larger markets are created, resulting in lower costs to manufacture products locally.
Economies of Scale: The larger markets created via trading blocs permit economies of scale. The average cost of production is decreased because mass production is allowed.
Competition: Trade blocs bring manufacturers in numerous countries closer together, resulting in greater competition. Accordingly, the increased competition promotes greater efficiency within firms.
Trade Effects Trade blocs eliminate tariffs, thus driving the cost of imports down. As a result, demand changes and consumers make purchases based on the lowest prices, allowing firms with a competitive advantage in production to thrive.
Market Efficiency: The increased consumption experienced with changes in demand combines with a greater amount of products being manufactured to result in an efficient market.
But there are disadvantages:
Disadvantages
The disadvantages, on the other hand, include: regionalism vs. multinationalism, loss of sovereignty, concessions, and interdependence.
It's basically finantial vs National pride; very big issue for most countries, especially powerful ones like Britian that use to rule the world.
So it's be a rich country and puppet state of the EU or a lesser rich country but have full autonomy.
Plus of course the CONTROL OF NUMBERS of immigrants, which is totally not the same as stoping imirants as thew remainers would have it.