I think the question is really twofold as Java in the enterprise and Java for the general hacker have very different use cases.
The enterprise space is where java still lives and breathes, and in that area I don't see play making any immediate headway. Spring and JSF will probably remain top candidates. I wouldn't clump JSF with struts just yet, with the release of JEE6 and JSF2 it has gained new traction. I'm no fan though and would love to see Spring dominate.
In the personal hacker space Play is great, but grails is pretty awesome too.
As for the next few years, I think it really depends on how Java 8 is implemented. I think the JDK has a healthy future, but If java remains a part of it will depend on a healthy implementation of closures