ssg, you have quite a gap in your education. Engine hours mean virtually nothing in the airline world, and haven't for three decades.
Airline engines are now removed either for cycle limits (rotating parts and pressure vessels) or for condition monitoring alerts. They may even be removed for excess fuel burn.
Any engine removed at 3500 hours would trigger a technical investigation by the airline and the OEM. It's not unusual for an engine to run 20,000 hours or more.
(When a KC-135R had a FOD during Desert Storm - 1991 - there was no USAF maintenance crew in-theatre that had any experience in engine change on the bird, and a contractor crew had to be flown in...)