I'm curious who it is these people you refer to are dealing with?
Fiat institutions? That would make sense. Else I can't see how there'd be any important amount of individuals out there carefully examining the provenance of the coins and checking them against any blacklists or what not. I'm not saying it doesn't happen but that seems like a somewhat far-fetched scenario.
Yes fiat institutions.
But I also have to tell you that personally I have avoided dealing with certain private parties (as a BTC buyer) because I felt pretty confident their coins would have really ugly histories and could cause problems for me in the future even though I had no immediate intent to deal with a fiat institution. So I simply took my business elsewhere, with probably some small cost, but it was worth it to me to avoid the risk.
As long as those fiat institutions are major ecosystem participants -- and they are -- their perspective matters, and not just to those dealing with them directly.
More resourceful individuals will show up on the marketplace that won't be bothered by such folklore.
When you use words like "will" you come off like an idiot or a religious fanatic. No one has a crystal ball. Things may work out that way, or they may not.
I'm personally far from convinced that Bitcoin (or any present cryptocurrency) "will" have a marketplace of note at all in the future, which further makes such statements rather ridiculous. It's success seems highly speculative.