They can go anywhere from 70k upto 100k. Ours had gone at 74k, we thought it was the clutch, when it went in he had it all apart and the pressure plate was on its way out and the flywheel was fucked.

With respect, if your mechanic is saying your flywheel will last the life of the clutch he's not very familiar with DMF's. Very unlikely it will last another 70-100k therefore costing you again to have it all apart and replace the DMF.