Make a prediction for long enough, and it is apt to come true. Brazil is a vast country with a large population and prodigious natural resources. In recent years, huge oil deposits have been found in deep water off shore. And Brazil has always had vast hydroelectric potential. The preconditions for economic success have always been there for Brazil, which is why the country has been touted as the next great growth area for most of the Twentieth Century. What has always held Brazil back has been poor governments (which existed largely to enrich the governing class and preserve the perquisites of the wealthy) and an impoverished population. Over the last ten tears this has changed, and today Brazil is one of the fastest growing countries in the world with a decent per capita GDP and rapidly rising living standards. The World Cup will be played there in 2014 and the Olympics in 2016, which should bring Brazil even greater worldwide exposure.
The stamps of Brazil have always been among the most interesting in the world and can be very specialized. The first issues have always been expensive, but there are two areas of interest for a budding specialist that are still untapped. The perforation and watermark varieties that proliferated from 1890-1940 make for interesting collecting. The stamps are inexpensive, and many finds of difficult and even rare stamps are still to be made if you can find a large unchecked group of these stamps (and it isn't too difficult). And second, the mint stamps after WWII, and especially from 1980 onwards, were neglected by dealers when they came out. As there have never been enough Brazil specialists to put away many of these stamps, should the stamps of Brazil become popular these stamps should rise in price.
The philatelic paradigm that predicts higher prices has two preconditions. First, a country needs an educated population with rising real incomes. It is from this group that newer collectors will emerge. And second, the country needs a large enough population that the number of new collectors (and remember that even in the best of all philatelic worlds, stamp collecting appeals to only a small percentage of people) will be large enough that prices of older material will begin to rise. It is this increase in price that gives philately the boost (or street cred) that gives publicity and attracts even more collectors. The difficulty in predicting the future growth in Brazilian philately is this: Brazil meets these two criteria, as did China and Russia, two nations whose stamps have performed wonderfully over the last twenty years. But in other countries that also share these two conditions, such as the Philippines and Mexico, the record of philatelic growth has been more mixed. It is hard to know which way Brazil will go, whether it will become very popular or continue to be an interesting secondary philatelic country. But even if the stamps don't increase in price, the rewards of collecting this country are many.