Edward Snowden apparently is still looking to Latin America and there is plenty of parsing his open letter to Brazil. He's careful not to make a formal request, which would box Brazil in and possibly make it even less willing. But he says:
Many Brazilian senators agree, and have asked for my assistance with their investigations of suspected crimes against Brazilian citizens.
I have expressed my willingness to assist wherever appropriate and lawful, but unfortunately the United States government has worked very hard to limit my ability to do so -- going so far as to force down the Presidential Plane of Evo Morales to prevent me from traveling to Latin America!
Until a country grants permanent political asylum, the US government will continue to interfere with my ability to speak.
I read that as a quid pro quo.
Dilma Rousseff would have to decide that a long-term break with the United States is desirable. Whoever takes Snowden cannot have good diplomatic relations, period. Therefore we would expect a government to do so only if it saw long-term gain in antagonizing the U.S. It's hard to see that in Brazil.
Of course, the U.S. will be sending private signals not to accept, but let's see if it does anything public. Screwing around with planes helped lead to Nicolás Maduro's asylum offer, which originally was not forthcoming.
Isn't it interesting, too, that Snowden wants Brazil, which has not said yes, instead of Venezuela, which already has? Venezuela is just not a stable enough place these days.