Some things can clearly be discerned from the available evidence, but others are murky.
There is a possibility that people freed from slavery because it had become unpopular among the states practicing it would have had less acrimony directed at them.
I think much of the later acrimony was caused by their voting as a block for the hated Republicans who were responsible for so much devastation in the South. That was certainly the original reason why the Klan formed. It was to counteract their usage as a tool to keep electing Republicans who would vote contrary to the interests of white southerners.
Had slavery just faded away, there is a likelihood that the black vote would have been more or less equally divided between the two parties, as the white vote used to be.(but is now lopsided heavily Republican.)
I'm not sure they would have respected black people's civil rights though even without the acrimony, because many white people of the time simply hated blacks because they were of a different race. Northerners especially did not want blacks in their communities, and this was one of the primary reasons Northern states wanted slavery abolished. They wanted blacks kept away from them.
Would it have been better or worse for black people?
I think in some ways it would have been better, and in some ways it would have been just the same.
What somewhat bothers me is the likelihood that without the abuses, people would simply tolerate the second class citizen status they would have had.
With a more tolerant attitude towards blacks, there may never have built up sufficient outrage over their condition to result in the societal change that happened as a consequence of egregious abuses against them.
Modern society might have ended up somewhat more backward than we are now. Maybe. Maybe not.
Maybe they would have had greater financial wealth, and created a greater role for themselves in the economic conditions of society, and therefore be in a position to find respect from whites just by being good and successful people.
Like I said, some things are just not that easy to see, while others seem pretty clear.
Agreed - and agreed. There were miscegenation laws in several Northern and Western states, along with restrictive covenants for housing, cemetery burials and the like. The same with poll taxes which were found in some Northern and Western states. Pernicious legislation such as grandfathering in payment of the poll tax was eventually struck down in Guinn v. United States .