What do you mean less and less famous riders are coming back.
Everyone who rides the TT is famous to the TT fans!
Would you have heard of Moodie if he hadn't won TT's, or David Jeffries or Joey Dunlop?? ( a bit of an exaggeration maybe).
But TT riders are special in their own right and they become famous because of the TT. "Famous" riders in the past have packed it in but they were replaced by by others, Hislop, Jefferies etc. Achievements of "current" winners will never be undermined because "famous" people don't turn up. It is about racing not constantly breaking records.