I was commenting on an earlier answerearlier answer, but it was getting big, so I thought I'd spin this out.
Any new language can only succeed if it capitalizes on an emerging frontier in computing.
Previous examples:
- C for Unix
- Objective-C for iOS
- Perl and PHP for back-end Web 1.0
- Python and Ruby for back-end Web 2.0
- Java for the back-end Internet-enabled enterprise
To answer your question, JavaScript was the language for Netscape Navigator back when that was the dominant browser. Specifically, it was the language for dynamic front-end development.
The next big language will have to solve another frontier. There still seems to be a land grab in the back-end web development space. Plus, mobile computing isn't totally solved, despite Apple's current dominance. Also, there's the emergence of multi-core and cloud computing, which is something that many languages are attempting to capitalize on (like concurrent languages like Erlang and Go, or functional languages like Haskell and OCaml).
Entrepreneurs have an expression along the lines of, "find a someone on fire and sell him a fire hose". So if you want to introduce a new language, whose fire are you putting out? Every new frontier in computing brings a whole host of headaches; so supply some aspirin and you'll be golden.