Well, Java can run "native", it just needs the native code dependencies of Minecraft compiled for ARM (but contrary as you implied, never heard of it).
I found another software, named ExaGear Deskop by Eltech, basically doing what I described, Binary Translation, and it should be faster than QEMU by some magnitudes, because it's not emulating the x86 opcodes, but just translates them once to ARM (as far my understanding, never tested it). It costs some money tho: http://eltechs.com/product/exagear-desktop/
Check this: http://linuxgizmos.com/emulator-brin...o-arm-devices/
Meh, on Eltech they write it's working on every Raspberry...
Only problem is:
ExaGear is based on binary translation technology, and requires ARMv7, which means that it should run on mini-PCs and SBCs that use Cortex-A8, A7, A9, and A15 system-on-chips. However, it won’t run on the ARM11 (ARMv6) SoC found on the Raspberry Pi. It also does not support applications that require kernel modules. It currently requires Ubuntu (v12.04 or higher), but will soon support another, unnamed Linux distro.
Too bad if you have an old Rasperry PI with ARMv6. The new "Raspberry Pi 2 Model B" is using an ARMv7 though, which Rasperry you got?