There are tons of other languages like that as well, most software developers know at least 2 or 3 of course but there are newbies who are good at just one. Think of blockchain developers like that, just a software developer who learned Java, than phyton and now blockhain, and applies for that kind of jobs, its gonna get only bigger.
Exactly, so if you are a software developer who have that kind of skills, you should at least jump on the bandwagon and go with blockchain technology. At least you are going to be flexible and more options to get a job in the future. And this has just started, this is a niche market pretty small if you look at it today.
But down five years from now, more company are going to shift from their legacy database and move to blockchain because of the many advantages of it. So it's a good thing to have a plan b for software developers, learn blockchain and you are definitely in for the future.
I don't think it is worth it to study blockchain technology for a job because the field is really niche and the amount of available jobs are really low. Why would companies move over from traditional databases to a decentralized one? Blockchain databases are slow and costly compared to what we have now.