Mike Busch has over 4,800 hours on 9 of his 12 cylinders
That depending is 3 to 4 lives this from here on in is in the danger zone from my experience. Hi heat is not the only thing that is going on. The metal is changing taking on what has been burnt in the combustion process as well fatigue is the biggest killer of cylinder's that also needs to be addressed.
They don't last forever.
Also there is a lot of difference between a train wheel and a removable cylinder on an aircraft wheel, And occasionally they also do let go as I recall Germanys worst train accident was caused by a wheel failure.
Cheers