I fully agree that C++ is much, much, worse than Java. The wonder is that people still use it for major new projects today. At least there are better options than Java available now (I don't know what the state of art was in 2002 that well).

If you got together an "above-genius-level" programming team, they could design and implement their own language while they were waiting for your FAI theory. Probably they would do it anyway on their own initiative. Programmers build languages all the time - a majority of today's popular languages started as a master programmer's free time hobby. (Tellingly, Java is among the few that didn't.)

A custom language built and maintained by a star team would be at least as good as any existing general-purpose one, because you would borrow design you liked and because programming language design is a relatively well explored area (incl. such things as compiler design). And you could fit the design to the FAI project's requirements: choosing a pre-existing language means finding one that happens to match your requirements.

Incidentally, all the good things about Java - including the parallelism support - are actually properties of the JVM, not of the Java the language; they're best used from other languages that compile to the JVM. If you said "we'll probably run on the JVM", that would have sounded much better than "we'll probably write in Java". Then you'll only have to contend with the CLR and LLVM fans :-)