I doubt that. Many languages invented before Java have already been qualified to fulfill cross-platform requirement in almost all fields except GUI. And look Java did what to GUI? Almost nothing. Java's GUI sucks, and instead of providing cross-platform, it created a new platform (recommend the use of Metal Look-and-Feel?). If your whole solution to make people working on two platforms feel better is to create the third platform, what's your point? Does people who are willing to get unified user experience have to pay money to Microsoft and Sun and Apple, and then resort to Java to get the same Look-and-Feel?
More over, all users I encountered, except developers, using one single OSs dominantly. So if you want to offer your app on multiple platforms, good, but only make the functionality cross-platform, not the user experience at the GUI level. Your cross-platform app is meant to make the same functionality accessible from different OSs, not to enforce the users of an OS experience what they should feel in another, or worse, in another new.
I think some people eventually realize GUI is of so high level of complexity and all different GUIs of different OSs can not be abstracted with a unified model in such detailed level like Java Swing.
So write once, test everywhere, for non-GUI? OK, C and other language already do that.
For GUI? No improvement from Java.