The sound card works rather well with the TCB and doesn't need much more in that regard. However it has the ability to be used directly with standard RC gear (like the Benedini) and that is the part that is under development now (lots of coding required). I suspect more people would actually use it that way than with the TCB. One could try to push it forward as-is but I think it is better to have as much of the development done prior to production otherwise I will be swamped with feature requests the minute people get their hands on it. I will be swamped anyway but at least not so bad as if people know there are large functionalities promised but not completed. But even making progress now is often difficult because I only have a limited amount of free time - this stuff is not my job. So things progress slowly
After all that then yes there is the challenge of finding someone to produce it. The costs - I don't know what production costs will run to, it depends on many factors, but what I do know is that I don't have the money to shoulder them, so some manufacturer will have to be willing to take those on. That is a tough ask and there is no certainty we find someone willing to do that.
Finally, there is even another challenge, maybe the biggest one of all - that is getting decent sounds for it. I am not making sounds, I am making a device that plays sounds. Somebody or some people will have to create sound files for it. Most end-users don't want to mess with that task which in actuality is extremely difficult to do well.
So for the time being as well as the foreseeable future - consider the TCB as it is now and just take into account that if you want to use it you will need to buy a Benedini or Taigen sound card or go without sound. This other project can not be promised at this point nor can I predict when or if it will be available.