It'll kill you no matter what. The body simply can't last much longer than a century, period, just as machinery eventually breaks down. Some tortoises last for at least three to four centuries.
Many trees can last for millenia.
There is no evidence whatsoever that even given normal bodies damage caused by the aging process could not be substantively repaired. Assuming you can repair the damage to the body done by aging, there is no reasonable reason human life could not be extended by at least a century, and there is probably no reason that, barring accident, you could not live in a standard issue body for millenia given periodic repair on the subcellular level. All of this assumes that people will choose to remain in unmodified bodies, of course. Yes, I do. The difference is that I'm comfortable with this fact.