I am not sure this is true generally: the JVM has been able to use "Compressed OOPS" aka 32bit pointers to objects managed by the VM in 64 bit platforms for a few years, even without any support from the OS.
Off course it's better when language/VM implementer take this issue into account, but for those who doesn't, just building a VM/interpreter for x32 architecture can be the only workaround.
