I think that developers would have learned to write CBL whatever the language. The hype of the web combined with the CBL being the only language available for client side programming practically guaranteed its success, whatever the shortcomings of the language itself.

Note that VBScript were much more familiar to many developers, because VB was one of the most popular language at the time. But it fell by the wayside because it was not supported at ubiquitously as JS. (It was also a much worse language than JS, but that was not the reason it failed.)