Trade Blocs: Wave of the Future?

[prog_expat]

(cross-posted on politicsforum)

I've recently become very interested in the topic of trade blocs, due to the continuing debate over NAFTA, news over the growth of the EU, and the process, currently underway, to merge Mercosur and the Andean Community (which is of interest to me as I recently moved to Argentina).

We've (I created the individual images, my wife put them together to make a movie) created an animation of the development of the current trade blocs and regional agreements (not all, obviously, just the major ones), from the formation of the ECSC in the aftermath of World War II till today. It's far from perfect: I didn't bother separating East Germany in the early years, marking the remaining European colonies (and US territories) since I'm not sure about the membership status of each one, and so forth, but I think it does the job of demonstrating the emergence of the phenomenon.

Based on current projections and plans, the world may look slightly different in 2020. Highlights include:

1. The merging of the current EAC nations into a unified country (the East African Federation), if Tanzania's citizens can be assured that it won't lead to them being on the losing end of a land grab
2. The ascension of Albania and the rest of the former Yugoslavia to the EU, provided the reforms needed to allow the EU to grow past twenty-seven member can be put through, the candidates continue to move forward with the needed reforms, and the Republic of Macedonia, Greece, and Cyprus can come to an agreement on the name of the RoM
3. The merger of Mercosur and CAN (including associate members) to form Unasur, which would combine almost all of South America into one bloc
4. The ascension of Yemen to the CCASG/GCC
5. Continued enlargement of the Eurozone (all EU members except the UK and Denmark are bound by treaty to adopt the euro sooner or later, although an exception may be made for Sweden)
6. The introduction of the Khaleeji (unified currency) in the CCASG/GCC
7. The introduction of the East African schilling in the theoretical EAF
8. The introduction of the Eco in select ECOWAS nations
9. The introduction of as yet unnamed common currencies for Unasur and SACU
10. Preparatory work for the African Union and Pacific Union

What do you think has lead to the growth of this phenomenon of countries self-organizing into regional blocs? What pros and cons do you see for regional blocs? How far do you think the process will go?

World map from Wikipedia, The Gimp used to modify it for the different years, iMovie used to create the movie file.