Slavery is something of a special case, because the cotton gin made it so much more economical its lifespan was extended at least a century. Beyond the Civil War via sharecropping and Jim Crow, and the former was a function of class rather than race discrimination that fostered the latter: As long as white sharecroppers had Jim Crow they were not the dregs of society, and the clung to it desperately as a result.

Anyway, no, Southern businesses were in no risk of going under for refusing to hire blacks in the '50s. Neither were Northern ones; if segregation were a purely Southern phenomenon the SCOTUS case that struck it down would not have been brought against Topeka, KS (a state infamously and bloodily formed by Free Soilers in a prelude to the Civil War.) However, the Equal Protection Clause was enough to decide that case and overturn both Plessy and the segregation dependent on it. That is not to say other remedies to restore universal liberty (e.g. the Twenty-Fourth Amendment) were not necessary and invaluable, but the most effective WERE universal (ibid.) Whether affirmative action quotas have done more harm than good remains an open question fifty years later.

I find it hard to support the notion Brown, the Montgomery boycott, the March on Washington and various highly publicized reaffirmations of the Equal Protection Clause would have made modern society any more discriminatory absent anti-discriminatory laws for the private sector. Businesses could get away with discrimination without losing custom when it had public sanction; removing that sanction removes the respectability on which that custom depends.

Chik-fil-A is doing alright now, and part of the reason is that much of their customer base already consisted of people who shared their views of homosexuality (et al.) However, much of it did not, and the backlash they have already experienced is enough they have begun withdrawing funding to overtly anti-gay organizations. Facing a choice between their religion and their wallet, I think we both know which the "Christian" right chooses every day of the week and twice on Sunday.

However, and this cannot be stressed enough, whether or not market forces drive discrimination from private businesses the fact remains they ARE private businesses. Yes, we want to eradicate bigotry, but not at the cost of eradicating independent thought and freedom. Unfortunately, people MUST have the right to bigotry, though if they make it the pretext for crimes they are as much (but no more) subject to prosecution for those crimes as everyone else is. In this case, I think the market can largely banish bigotry, but where it does not, where people are willing to patronize bigoted business owners, they must have that right if society is to truly be free. We dare not dictate, by majority rule or otherwise, how people believe, or dispose of their own property.