The world's top economy in 2050 will be China, followed by the United States. No surprises there - since China's reforms in the 1980s, economists have said it's not a question of if, but when, China's collective economic might will top the U.S.

But among the smaller, developing nations, there are several surprises by HSBC prognosticators:

* By 2050, the Philippines will leapfrog 27 places to become the world's 16th largest economy.

* Peru's economy, growing by 5.5% each year, jumping 20 places to 26th place - ahead of Iran, Columbia and Switzerland. Other strong performers will be Egypt (up 15 places to 20th), Nigeria (up nine places to 37th), Turkey (up six spots to 12th), Malaysia (up 17 to 21st) and the Ukraine (up 19 to 45th).

* Japan's working population will contract by a world-top 37% in 2050 - yet HSBC economists predict it will still be toward the top performing economies, dropping only one spot to the 4th largest economy. India will jump ahead of Japan to 3rd on the list.

* The big loser in the next 40 years will be advanced economies in Europe, HSBC predicts, who will see their place in the economic pecking order erode as working population dwindles and developing economies climb. Only five European nations will be in the top 20, compared to eight today. Biggest drop will be felt northern Europe: Denmark to 56th ( -29), Norway to 48th ( -22), Sweden to 38th (-20) and Finland to 57th (-19).

HSBC 2050 list of top economies (change in rank from 2010)

1) China (+2)

2) U.S. (-1)

3) India (+5)

4) Japan (-2)

5) Germany (-1)

6) UK (-1)

7) Brazil (+2)

8) Mexico (+5)

9) France (-3)

10) Canada (same)

11) Italy (-4)

12) Turkey (+6)

13) S. Korea (-2)

14) Spain (-2)

15) Russia (+2)

16) Philippines (+27)

17) Indonesia (+4)

18) Australia (-2)

19) Argentina (2)

20) Egypt (+15)

21) Malaysia (+17)

22) Saudi Arabia (+1)

23) Thailand (+6)

24) Netherlands (-9)

25) Poland (-1)

26) Peru (+20)

27) Iran (+7)

28) Colombia (+12

29) Switzerland (-9)

30) Pakistan (+14)

"If we step away from the cyclicality, there are two ways economies can grow; either add more people to the production line via growth in the working population, or make each individual more productive," the report says.

In other words, demographics - the size of your working population - along with the opportunities to flex that muscle help determine long-term economic trends. Big factors on the back half of that equation: Education opportunities, democratic governments or strong rule of law (a caveat that explains China and Saudi Arabia's high placement).

"We openly admit that behind these projections we assume governments build on their recent progress and remain solely focused on increasing the living standards for their populations," the report says. "Of course, this maybe an overly glossy way of viewing the world."

Chief factors that may derail economies moving forward, the report says: War, energy consumption constraints, climate change, and growing barriers to population movement across borders.

cnn.com