I don't know if this is a regional thing or what but besides prices increasing a little for wholesale there hasn't been a shortage for us for yellow tangs. In fact a local distributor will sometimes have upwards of fifty on hand in a variety of sizes. If I wanted to I could get dozens tomorrow without issue. The price increase that you see in retail stores is rather artificial as the price increase from wholesalers is rather small. Again this might be regional or maybe it feels like there is more of a shortage because it seems like websites like live aquaria are always out of them and selling small yellow tangs for about 120 bucks. Source: I own a fish store in Chicago lol.
I will say I believe and hope that captive bred fish are the future as it is obviously much more sustainable than wild caught fish, and I'm glad to see more people are getting captive bred fish when available.