Ext GWT Premium Member
There are a lot discussions about the monolythic nature of GWT apps on the forums. And there are some possible solutions.
The problem however will be with achieving a "tight" integration between your GWT modules. In other words, if you need to pass some data or behavior between your gwt modules you might run into issues (and come up with standard message passing mechanism). But I think "loose" coupling could be quite a lot easier...
I also remember that some folks mentionning that they just break up large GWT apps into modules loadable via iFrames - which might be another approach to the issue.
Regardless, I think having some kind of a standard "framework" that provides a variety of solutions to the problems could be quite useful.