How long will an iphone 5 or Any iPhone Last?

Not battery consumption --The phone itself, in a lifetime…
If it's taken care of very well, and not Stolen, dropped or battery replacements?

Well for life I guess. With proper care. I have a phone from 2005 & aside from a little wear on its main menu button it is still good to go. Perfectly functional.

The iPhone is much the same. Take care of it & it will last.

As long as you want, many still use 3GS today and thats now 3-4 years old. Some still use the original vs 3. Hardware keeps improving and eventually will want to upgrade though, but you can surely go quite a few years if you want.

That depends on how well the owner takes care of the phone. If you take care of the phone and replace the battery when it needs replaced it should last for 5+ years. That does not mean that a person would want to keep a phone for that long. But if someone is spending that much money on a phone they should keep it until it stops functioning.