I guess you could say Java still has relevance for non-free uses of Free Software. But if its main value is for non-free uses, it seems as if those users ought to arrange to pay for maintaining and porting it. That won't happen without somebody experiencing pain first, so maybe it would be better to wait for some.
On the other hand, I'm betting that when the first AArgh64 chips come out, if the code doesn't run right, the chips will be considered wrong, and they'll change the spec to match the code. That seems about equally likely to be good as bad. Probably the people doing the code generator should get in touch with any malcontents from the Aargh64 design team and see which of its choices ought to be overturned that way.
I do like that in the Dalvik execution model, your program must be prepared to be killed off at any moment, and to then jump up, Inspector Clouseau style, if anybody happens to look.