What GWT needs is a plugin model, maybe something similar to the way java servlets work but to have them be client centric. An example of this is a project called SOAFaces. It allows for the packaging of GWT applications into plugin modules called Weblets. These are pure GWT components that can be deployed and linked dynamically in a server environment and accessed by the client. A Weblet has a simple GWT API and a simple packaging specification for putting the Weblets into a JAR that can be distributed to any container that supports Weblets.
Well as you may have guessed, the SOAFaces framework facilitates this capability. In general it would be good for the GWT community to start thinking about components and how to package, share, and deploy them in dynamic environments.
For an example of something that already supports the SOAFaces specification check out the product JobServer. JobServer supports the concept of hot deploying of Weblets and compiling GWT on the fly. JobServer provides and integrated job scheduling environment and support for Mule and SOA.