As i said, the south states would go bankrupt imediately if they secede. I think Santa Catarina would actually be able to go by, but they would make just enough to pay their expenses as a functioning state, but couldn't invest in much more i believe.
They really depend on the goverment to succ resources from other states and give it to them so they can function. The ones who actually dont depend in anything are São Paulo and Minas Gerais. These two certainly could secede, but that would fuck up the rest of the country.