Brexit: What we know -- and don't -- about impact of shock vote

The U.K.'s vote to leave the European Union is reverberating in political capitals and financial markets around the world. But if the historic referendum was a clear statement of discontent in Britain, the political and economic fallout from the country's "Brexit" from the EU is far more uncertain.

To that end, here's what we know and don't know about the impact Brexit could have on the U.K., U.S. and Europe.

WHAT WE KNOW

U.K. goes shopping for a new prime minister. Or at least the Conservative Party does. Soon after British voters elected to leave the European Union, PM David Cameron announced he would step down within three months.

"The British people have made a very clear decision to take a different path, and as such I think the country requires fresh leadership to take it in this direction," Cameron said.

The Conservative Party, also known as the Tories, will choose a new leader, with former London Mayor Boris Johnson considered a strong contender. Whoever is chosen as the new prime minister will be under pressure to call a national parliamentary election.

The U.K. is likely to slip into recession. The U.K.'s vote to leave the EU was dubbed a "leap into the unknown" by Samuel Tombs, chief U.K. economist with Pantheon Macroeconomics. What he does know is this: "U.K. voters have opted for Brexit. If fully followed through, this will be an act of economic self-harm with global ramifications."

Tens of thousands of U.K. jobs directly tied to the EU's nearly $18 trillion unified marketplace could move to the Continent over the next few years, especially jobs in banking, manufacturing and pharmaceuticals. These companies benefit by being based where their EU customers are. Why be headquartered in a country outside the EU?

That's one reason T.D. Securities on Friday put the odds of the U.K. sinking into recession within the next 12 months at 60 percent. Meantime, credit rater Standard & Poor's said the U.K. is likely to lose its AAA credit rating, which it called "untenable under the circumstances."

Your 401(k) will take a hit. Stocks tumbled almost everywhere they are traded the day following the Brexit vote: London, Paris, Frankfurt, Seoul, Tokyo, Shanghai, New York -- all saw steep and swift drops measured in the hundreds of billions of dollars.

The thing is, most American investors' retirement portfolios include stocks from all those places. It's the nature of big business today. The giant companies that represent the majority of the stock market's value -- from American staples like Coca-Cola and McDonald's to global brands like Diageo and Samsung-- sell their goods and services all over the world. There is literally no place for an investor to hide.

"Europe is an important economic center. Europe matters quite a bit to the global economic picture," Jim Russell, a principal and portfolio manager at Bahl & Gaynor, told CBS MoneyWatch. "The uncertainty is what the markets are going to react to over the next few trading days."

"A lot of bets were placed on 'the remain' vote being successful, now those bets will be unwound," Russell added. "The reality of this vote has yet to unfold."

WHAT WE DON'T KNOW

Future of the United Kingdom? The United Kingdom consists of four nations, but could that drop to two after the Brexit vote?

Just two years ago, Scottish voters rejected pulling out of the U.K., but the withdrawal from the EU changes the equation. Scottish leader Nicola Sturgeon said a new referendum on Scottish independence is "highly likely" in order to remain in the European Union. Sixty-two percent of Scottish voters favored staying in the EU and Sturgeon said it was "democratically unacceptable" for Scotland to be taken out of the EU against its will.

Similarly, a majority of voters in Northern Ireland opted to remain in the EU. Now Northern Ireland Deputy Leader Martin McGuinness is calling on London for a referendum on a united Ireland.

"The British government now has no democratic mandate to represent the views of the North in any future negotiations with the European Union and I do believe that there is a democratic imperative for a 'border poll' to be held," McGuinness said.

Will other dominoes fall in the EU? Time will tell, but top EU officials are hoping to quash the prospect of copycats.

Manfred Weber, the leader of the European Peoples, the biggest bloc in the European Parliament, insisted that Britain would not get any special treatment in their deal to withdraw from the EU, which will be negotiated over the next two years.

"There cannot be any special treatment for the United Kingdom. The British people have expressed their wish to leave the EU. Leave means leave. The times of cherry-picking are over," Weber said.

Translation: Brits shouldn't expect to retain any of the benefits that come with being a part of the EU.

But that message isn't meant just for the U.K. It's also aimed at discouraging other members from wanting to leave the bloc.

How much the U.S. economy will suffer. Despite the immediate hit to the U.K., most economists think the short-term impact on the U.S. economy will be modest - for now. American exports to Britain account for only about 0.7 percent of U.S. GDP, according to Gus Faucher, senior economist with PNC Financial Services Group.

That means even if the U.K. falls into recession, as many forecasters expect, U.S. manufacturers who do business in Britain are likely to see only a small dent to earnings.

Another reason Brexit could benefit U.S. consumers and small businesses: The Federal Reserve is likely to push back its timetable for raising interest rates. With Fed Chair Janet Yellen last week citing the risk of a U.K. withdrawal form the EU as a reason the central bank was leaving rates unchanged, market watchers speculate that the next hike may not come until the fall - or later.

"While Brexit likely spells a stronger dollar and weaker U.S. exports than otherwise, it also should be associated with even lower longer-term interest rates -- a positive for the economy, in our view," said UBS economist Maury Harris in a research note.

But the fallout from the U.K.'s historic retrenchment will take years to play out. While financial markets are likely to stabilize in the days or weeks ahead as the dust settles from the vote, the geopolitical consequences for the EU and the eurozone are unpredictable, especially as other nationalist political movements around Europe push for their own referendums on whether to exit the union.

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    Alain Sherter covers business and economic affairs for CBSNews.com.