Unfortunately, I think you're right
I think a human being's DNA would have to be completely redesigned to enable a 1000 year life span. They'd design it from scratch with computer aided design like they due for microchips. That resultant person would be an artificial construct that looked like a person by not actually human (could not produce children with a nonsynthetic human). Definitely the stuff of science fiction but probably practical within 50 years.
Gary