Why shouldn't skill associations change as rapidly as technology, if not faster? It's not like you permanently pigeonhole yourself if you call yourself a javasc

Why shouldn't skill associations change as rapidly as technology, if not faster? It's not like you permanently pigeonhole yourself if you call yourself a javascript engineer. Having said that, javascript is pretty ubiquitous now and it only seems to be growing. I wonder what the odds are of it being replaced, given how slow the specifications evolve. Is there any reason to think it won't be here to stay for a long time?