I like the idea but I think it will have some serious challenges.
- Airsofters are a cheap bunch
- Warranties increase costs
- The only reasonable warranty is against DOA
- Any kind of "use / abuse" warranty is asking for trouble due to the nature of how the product gets used (upgrading, wear and tear, etc).
It is one thing for, say, SureFire to offer a lifetime warranty for their hard use products. But they're not selling what are basically plastic toys.