Ironic that you say that, minecraft, which is java and also OpenGL, runs Alooot faster than my computer on my HTC HD2 running android and no overcocking, so it's feasible. Also, i don't think we're that far, with the release of the Quad Core 1.5ghz NVIDIA Tegra 3 processor in Q3 2011, which can outperform Intel's Core 2 Series of processors we will be able to have really close to xbox 360 graphics on portable devices, i'm sure that with the current devices with Adreno GPU chipsets something can be done to optimize stuff in order for it to work. the whole thing is Done, the only left is to optimize, port and adapt stuff for it to work on android. prolly a week worth of sum'd work.
Tegra 3 in action.