"do you think that there will be many new ones?"
Yes, I think there will continue to be some new projects, and other projects will fall off. Apache isn't the end-all be-all of Java projects, however.
Several of the larger newer projects were under SpringSource's wing, and there continue to be new projects there. And there's Codehaus. And some Java projects under GitHub, Java.net, SourceForge, etc. Then there's Groovy, Grails, and related projects. JRuby (formerly at Sun, now at EngineYard) is Ruby, but it allows some reuse of other Java projects. Android (like the author states) is a subset of Java, so all of those Android app projects. Kindle's KDK is Java. Your cable box may even run on Java.
If you've been only looking at Apache for Java growth, you've been looking in the wrong place.
"Or how many existing projects will have any significant effort put behind them?"
The Java projects at Apache have had continued effort put behind them, but some of the people that would have put effort towards Apache projects have spread out into some of the places I mentioned.
"If Java at Apache flounders, the platform as a whole will also diminish."
That's BS. If Apache fell on its ass, Java would still survive. See all of the other projects I mentioned, plus all of the current Java jobs I mentioned.
Where "Java" itself isn't the new hot thing, Java is dominant, and things using/requiring Java are hot, for example- look at this Google trends of Java vs. Android to see what I mean:
http://www.google.com/trends?q=java%2C+android