I am not so sure what is "blockchain software developer" is really. Like any software developer can learn how to be blockchain developer ?  Or does it really require a set of language that is more blockchain oriented, or does it have its own language ?

Whatever the result it the future of blockchain looks bright but with the hype we had there is a lack of developer for it, there is already a lack of developers in the world since we need more and more of them whereas the human population can breed at a certain level and only so few of them could become developers so asking for something even more niche will take time.

Blockchain will get huge and be something we use daily in time but we require a bit more time for that to happen, probably in 10 or so years we will get there or at least get somewhere close to that.