I wouldn't think so. You're purposing that I swap the pinnacle of fish keeping that gives me the recognition of breeding a group of fish that most people can't keep alive for what essentially a slow growing color blob? Remind me what the cost pound for pound is when compared to a high end stingray? Also how many restaurants have a run of the mill tank with the fake coral and typical reef fish and how many have Rays? Saltwater tanks are everywhere, I think that's part of the attraction to fw Rays is the ability to branch out and be different is what draws most people to rays.
Sorry don't see that happening anytime soon.
On the flip side E Energy converted from reef to rays as did my dad when he transitioned to sw Sharks then he got me interested in fw Rays.
There are saltwater stingrays. In addition to stingrays saltwater has skates, eagle rays, guitarfish and sharks. Keeping saltwater fish alive is much more difficult then freshwater, including water changes to maintain water quality.