How hot is supersonic intake air? How hot is the air at the compressor inlet at supersonic speed? For instance the Concorde at mach 2.2 or other jet engines at even higher speeds.
The air entering the first compressor stage of the SR-71's engines could be as hot as 450C while at maximum cruise conditions. If that air got any hotter, it would begin to soften the compressor blades, and this put an upper limit on the speed of that plane.