This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
As of now it requires JavaFX runtime which has to be installed seperately along with the JRE. But going forward they might mostly bundle JavaFX runtime with the JRE.
I dont think its some sort of difficult/huge dependency to achieve. These days most of the OSs come with the JRE installed. You will not be able to execute java applications without the JRE.
For that matter if you look at other RIA technologies- all of the require some sort of external runtime to execute.