Banks, hedge funds, and other financial specialists may now consider life outside Hong Kong, a place known for its liberal economy and direct access to China.

So where could they go?

Singapore, Tokyo, and Shanghai are possible options.

In March, the three financial hubs were just behind Hong Kong in a ranking of the competitiveness of more than 100 financial centers.

So could these cities get more of Hong Kong's business?

Singapore has a lot of the same qualities that make Hong Kong attractive.

The city state has rule of law and an attractive tax system, and just like Hong Kong, it has the ubiquitous use of English.

It's also a major center for wealth management.

But Hong Kong has one really big advantage.

It's a gateway to China.

Hong Kong is part of China, but it has its own special legal and regulatory system.

Singapore of course, has got a lot of cultural affinities with China, and there's a big Chinese diaspora there, but of course it's a separate country...

And I don't think for Chinese companies or for Chinese officials, it's quite the same thing to list a business in Singapore as it is to list it right next door in Hong Kong.

As a result, Singapore's stock market has always been smaller than Hong Kong's.

Very roughly, the Singapore market is about a quarter the size of the Hong Kong market in terms of the capitalization.

In September, when the Hong Kong Exchange made a surprise takeover proposal to the London Stock Exchange, the LSE's board rejected the order and said it actually preferred Shanghai as a direct channel to access China.

Shanghai already serves as mainland China's most advanced financial hub, including bond and stock markets capitalized at trillions of dollars.

Its exchange is already larger than Hong Kong's, and it is forecast to grow much further in the coming decades, but being in China can also be seen as a disadvantage.

China still operates capital control so you can't take money in and out of the country very easily, given that there's quite a complicated and opaque legal system, and so often companies feel they're operating in an unfair system.

For years, the government has been liberalizing the financial sector to attract foreign institutions and their money.

We will encourage and support bold and creative steps by Shanghai to advance investment and trade liberalization and facilitation.

But the bureaucracy so far has hindered Shanghai's ambition as a truly global financial center.

Tokyo is the capital of the world's third largest economy.

It is a place where companies enjoy the rule of law and which boasts deep markets.

The city has more Fortune 500 companies than anywhere else.

- And in late August... -Aramco might list in Tokyo.

The city made big news with a Saudi Arabian oil giant.

The Japanese authorities might be comfortable with a slightly lower level of disclosure about things like reserves for example, which might make it easier for Aramco, which is a very politically sensitive company to list in Tokyo.

If Tokyo won a listing of Aramco, that would be a really big feather in the cap of that stock market.

But there are factors holding Tokyo back.

Taxes are higher than in Hong Kong or Singapore.

Tokyo also has stricter VISA requirements.

It's also a less cosmopolitan place.

Language is a big barrier.

It can be difficult for companies to find employees who have a good command of English.

The country was rated 32nd in latest HSBC list of top expat destinations, way behind even mainland China.

Many financiers say that Hong Kong is still the only city in Asia to offer the combination of the rule of law, an open capital account, and a convenient base for jumping into the Chinese market.

Yet the long months of protests are already taking a toll.

Chinese E-commerce giant Alibaba recently put a blockbuster listing there on hold for instance.

Hong Kong is scheduled to keep its special status as a semi-autonomous region until 2047.

But as Beijing's grip on the territory increases, so does uncertainty about what might happen in the near future.