The United Kingdom has stunned the world by voting to leave the European Union.

There will be wide-reaching consequences across the continent, but one topic that has not been part of the discussion is football.

Undoubtedly the most popular sport across the continent, the "beautiful game" has also grown in to a multi-billion euro industry within the United Kingdom and across the EU. Today players are able to move from one country to the next for huge fees and with very few obstacles.

A report commissioned by the BBC concluded that should Britain vote to leave the EU, the English Premier League – regarded as the most popular league around the world – would be “radically changed.” Moreover, without the free movement of labor that comes with EU membership, more than 400 players across the United Kingdom's four football federations could immediately lose the right to play within their leagues.

Currently players from within the EU are free to play in the UK, yet those from outside the union must be granted a work permit to gain entry. Such permits are based on the FIFA ranking of the player in question and then how often the player in question has played for his country in the past two years. Following the result of Thursday's vote, players from around the continent could be forced to undergo similar measures if they hoped to move to a club in England, Scotland, Wales or Northern Ireland.

Such changes may have a dramatic effect on the Premier League. Its chief executive, Richard Scudamore, had repeatedly spoken out in favor of remaining within the EU for the sake of the organization he heads.

“There is an openness about the Premier League which I think would be completely incongruous if we were to take the opposite position,” said Scudamore in an interview with BBC Radio 5 this week.

A whole new set of rules

However it's not just the Premier League that could feel the squeeze. Leagues across Europe might have to completely change the way they do business. None more so than the German Bundesliga, which regularly trades players for millions of Euros each season with the Premier League.

Bastian Schweinsteiger is one player brought from the Bundesliga to England

Last summer the English top division spent close to $226 million (220 million Euros) on players from the Bundesliga, most of whom are German nationals or from other EU nations. As things stand these players are free to move from Germany to England with very little red tape getting in the way. When Britain eventually leaves the EU, it would be far harder to sign such players. All of a sudden, Bundesliga stars would be far less appealing to the cash-rich Premier League clubs.

An editorial in Kicker magazine last summer tackled the Bundesliga's dependence on Premier League money by stating that the “super rich from the Premier League are pumping money into the Bundesliga cycle." Kicker argued that in fact, the Premier League's riches were an advantage to the German top division.

"Clever scouting, solid education, a high level of competition, profitable sales - all this pays off, quite literally," the magazine wrote.

Although Bundesliga fans may welcome the thought of German teams holding on to their best players, it would completely disrupt the manner in which some of Germany's biggest clubs operate. Borussia Mönchengladbach or Bayer Leverkusen profit from Premier League clubs driving up the price of stars. Although they may not be happy having to sell the likes of Granit Xhaka or Kevin de Bruyne there's no doubt that they at least take some comfort in selling them at the absolute highest price.

Ultimately, European football is an open market, and it will eventually find ways around any new trade restrictions put in place by an independent UK. But Brexit will lead to all sorts of uncertainty in the world of sports finance, all of which may have a negative effect on the Bundesliga.