Javascript isn’t going away. But neither are 1′s and 0′s. But one has to wonder what type of project or team that was looking to grow and build web-based, rich-client applications would actively choose to use Javascript on it’s own now.
For my part, there’s only so much patience I have taking on the burden of supporting multiple browsers and dealing with performance issues. Particularly if I’m Agile, and I’m focusing on delivering so much value so quickly, it’s very hard to explain to a client that the underlying technology creates significant overhead that adds drag to the project. This is an even tougher sell – particularly when you’re open with your client, when alternatives that meet the non-functional needs exist.
For your standard web applications that aren’t as client-centric as today’s RIA applications, it’s certainly true that you are barking up the wrong tree with GWT. Rails, Grails, and Zend can all give you the non-enterprise delivery tools that accelerate development from the server-side and leave the Javascript problem to be solved in a less holistic, more tactical way.
But it’s hard to argue now that anything short of the compilation semantics of GWT is useful in the RIA realm (without the need for a intermediate runtime, of course.) Javascript is too costly and too brittle in large-scale applications to be subject to human hands. If you’ve hired a contractor to build you a web-based RIA and they’re not using GWT – it’s well worth your wallet to ask them why.