[randywebb]

No they won't wear "out" -- not within your lifetime anyway.
The metal may get worked enough that its properties alter at some point. Where that point would be, I don't know. Many tens of thousands of flexes at least.

More important is to inspect them carefully for any pits, cracks or other surface defects. All rubber and plastic items will need to be replaced - maybe every 5 or 10 years. That includes brake hoses.

In NH ore anywhere in the northeast or midwest, I would worry a lot about rust and pitting. Those lead to breakage.

If you replace the bars, I'd get a quality hollow bar (Sanders). They cost little more and save a bit of wt.