Interesting thread so far, lots of thoughtful arguments/comments. I suspect of this forum had been around in the 1920's, we would have been arguing how will they ever get these new fangled gasoline aero-engines to be reliable.
I'm completely confident that the engineers will ultimately lick the problem. It may take a paradigm shift. My guess is SMA will ultimately make the engine liquid cooled.
However, there is another problem on the horizon for diesels that no one has mentioned. The production of diesel particulates, aka soot. Diesel particulate filters cure this problem at the expense of power and efficiency, then there's the need for active or passive regeneration in the DPF (burning off the soot in the DPF), but periodically you still need to remove the DPF to clean out the accumulated ash plugs. Don't even for a minute think that aero engines will forever escape the EPA who will eventually mandate DPF's for aero-diesels.
I've installed a water/meth injection system on my RAM3500 which keeps the DPF clean as a whistle and almost never have to do a regen.