Perhaps is Slavery was not abolished in the late 1880s or if it was done more gradually? No, that'd be even less realistic, right?
The problem with the end of slavery again falls in the effects of the war. For the government, the so called "Law of the Free Womb" of 1871 had already solved the question. All the slaves born after that year would live with their masters until they reached the age of 8. Then, or the master would receive an indenization from the government and set free the slave, or he would keep him until he is 21, with these extra years of work being counted as indenization. With this solution, everybody expected a safe and gradual end for slavery, even if it meant that there would still be slaves well into the early 20th century.
However, the abolitionist campaign got strenght after that, especially in the early 1880's, by pressure of the Army, the Church and the Republican and those who defended the "whitening" of Brazil by bringing European immigrants. When the provinces of Ceará, Amazonas and several municipalities of Rio Grande do Sul decided to abolish slavery in 1884, without waiting for the central government decision, it created a dangerous precedent. Other influence was the fact that the coffee planters of West São Paulo (the region to where the plantatiosn were suffering the greatest expansion) soon realised that bringing immigrants to work was more profitable than keeping slaves (that were becoming increasingly expensive by that time, 30 years after the end the Transatlantic slave traffic). Only the traditional and declining coffee plantation areas of Rio de Janeiro and Paraíba Valley (Northeast São Paulo and Southwest Rio de Janeiro) kept their attachment to slavery.
Then the Parliament was forced to vote the Sexagenaries Law in 1885, that stated that all slaves above 60 should be freed. But again, in order to have it passed, they included an article that stated that all these sexagenaries should work five more years as indenization to their masters.
That's the word that was he real trouble involving the abolition: indenization. Most of the farmers by the 1870's and 1880's knew that slavery would cease to exist. The problem is that they wanted to receive indenization for the loss of their "property" and some kind of economical help to adapt their production to a "wage system". But the government couldn't offer this economical incentive, due to the crisis in the public finnances cause by the war between 1864-1870. And the farmers knew it. Remember the law of the Free Womb? Well, from all slaves born after 1871, only 118 were "bought" by the government to be freed before they reached 21, partly because the farmers wanted to keep their manpower, but also because the government couldn't afford to pay for them.
So, I think the end of slavery could have been delayed, but not that much. Many other political reforms were being planned at the end of the reign of Pedro II exactly in order to counter the growth of Republican sympathies, and if it hadn't been abolished in 1888 it probably wouldn't last more than five years.
