You should be able to ride the rim and bring the bike to a hault at that speed. You might damage your rim, but in that kind of situation it is better to damage the rim than yourself.

If you did crash at that speed you would obviously do a bit of damage to yourself depending on which parts of the body hit the ground, but I don't think you would die unless you landed on your head. We have this massive hill here in which some of the blokes reach 60mph and more going down and every now and again you hear a horror story of someone crashing, but I don't think we have a had a fatality yet.