Snake Featherston
Banned
I suspect Brazil outlawed slavery in large part because everyone else had given it up and it was starting to look really bad. If you have a relatively powerful slave-holding Confederacy around as an ally there's less reason to do it, especially if the Confederacy can make the transition to industrial slavery (i.e. slaves working in factories).
I don't think it's a sure bet slavery is gone before the turn of the century. It may take a war to finally end slavery if the Confederacy's identity is tied up in it.
The thing is that Brazil also abolished slavery because it was ruled by an autocracy able to push through abolition, albeit at the cost of its continued ability to both exist and have a monopoly on political power. This factor does not exist in the Confederacy, and due to the nature of the CS constitution and the inevitable chaos caused by Northern war policy no matter how the CSA wins is even less likely to do so do.
And the equivalent of the fall of the monarchy in the USA is a US reconquest when a Confederate Pancho Villa expy starts raiding the southern US border.