DSP for Sonar

Some day we see a dsp hardware specific to Sonar?

If anything it would make more sense to simply make use of GPUs which are powerful stream processors these days. Dedicated DSPs make little sense in the days of cheap powerful CPUs and GPUs.

No, what DPSs offer is doing specific tasks fast and particularly at a low cost (monetary and power) per flop. They are akin to ASICs. That's fine, but you can replace any specific silicon with software and enough power behind it. Well, we have a lot of power in our computers these days. Hence doing things in software often makes sense. Audio is an "easy" task these days. You can usually do what you want on a general purpose chip no trouble, so that's the way to do it, since you have one of those.
 
DSPs make sense for devices that are application specific, or have lower power/cost requirements but on a PC you have a big ole' CPU so might as well use that.
 
Also with regards to GPUs depends on the task, and the GPU. They change pretty rapidly. They have gotten more general and better at doing things that used to give them trouble (like branching). They are now well and truly stream processors.
 
The point is, a dedicated DSP is getting to be a pretty hard sell. You'd have to make something cheap enough that it is less than just getting a more powerful system, and it would have to be for something that is giving people trouble.