Who will benefit from a Brexit brain drain?

Brexit is raising hopes about a reverse 'brain drain' as migrant workers head out of the U.K., but experts say Britain's losses might not mean gains for central and eastern Europe.

Poland's Deputy Prime Minister Mateusz Morawiecki this week said Brexit would allow the government to invite some of its emigrants back home, according to Reuters, putting a positive spin on fears of job insecurity for thousands of workers across Britain.

Krakow, Poland
Maria Swärd | Getty Images
Krakow, Poland

"Central and east European governments hope for a 'reverse brain drain', especially the Baltics, which have experienced substantial outflow of young educated people in recent years," Otilia Dhand, a senior vice president and eastern European expert at Teneo Intelligence told CNBC via email.

"But others, too. For example, Hungary is suffering from labor shortages; most notably health care and IT – exactly the kind of workers that have all left for London," Dhand said.

Estimates by the Office for National Statistics suggest that between the first quarter of 2015 and the same period this year, non-UK nationals from the EU working in Britain increased by 224,000 to 2.15 million

The influx of workers to Britain is believed to have hit a nerve with a number of U.K. voters, with the Vote Leave campaign promising to crack down on immigration.

But with banks like Goldman Sachs predicting a mild recession for Britain in light of the Brexit vote, an economic slump could drive migrants out much quicker than new immigration laws, Richard Jackman, a professor of economics at the London School of Economics told CNBC.

"If there is a recognition that the level of immigration hadn't been much affected by EU freedom of movement, but it's just high because the economy is growing and it's easy to get jobs, then restrictions, in terms of quotas (don't really matter)," he said.

Goldman Sachs economists said U.K. GDP would take a 2.75 percentage-point hit over the next 18 months as a result of the deteriorating terms of trade and uncertainty around Brexit.

Furthermore, Mark Mobius, Executive Chairman of Templeton Emerging Markets Group, told CNBC Wednesday that Brexit could shift manufacturing to eastern Europe," but only if "eastern European countries step up to the plate and really encourage investment in a more favourable way than they are now."

While it's still unclear whether Britain will send foreign workers out or even stem inflows, experts say skilled workers would likely seek employment in other EU economies before returning home.

"The sense is that it would be mostly unskilled workers returning home," Dhand said.

"(But) in Poland, such jobs have already been taken by Ukrainian economic migrants in the meantime."

That could put strain on eastern European countries' labor markets, she explained, though "the direct economic fallout from the potential return of migrant workers would be limited."