Regarding remittances, I don't believe any blockchain technology has made a significant dent in the market. If you have data otherwise, I'd be interested to see it. But I live in a neighborhood where there are a lot of money transfer places, and all of them seem to be conventional.

As to the rest, I think we're talking about light financial crime. (Light because the heavier sort isn't big on having a permanent public record.) It's hard to know, of course, but is this usage going up or down? I had the impression that KYC/AML efforts were putting a big crimp in it. Either way, it seems self-limiting to me, in that significant success invites more attention from various authorities, which strongly discourages participation from people who would like to remain on the right side of the law.