Hi KitSnicket,
There are certainly many mattresses that can last for much longer than 7 - 10 years (and one of the goals of the site is to help you find them) although after 10 years the limiting factor in the useful life of a mattress may be the changing needs and preferences of the person sleeping on it.
Post #4 here has more information about the many variables that can affect the durability and useful life of a mattress relative to each person. You can also see an example here of a latex mattress that was in use for almost 50 years but even for latex this type of longevity would be very unusual.
There are also some local manufacturers who can rebuild a mattress by replacing just the layers that have softened or broken down.
Component mattresses with zip covers that allow for individual layers to be replaced as necessary without having to replace the entire mattress can also be a good option.
There are also many people who have done mattress surgery to replace the lower quality materials (that unfortunately are very common in the mainstream mattresses that dominate the industry) and replace them with higher quality materials (see post #2 here).
Finally there is also more information in post #2 here about recycling mattresses.`
Of course the first goal is to avoid most of the mainstream mattresses that use lower quality and less durable materials in the first place :).
Phoenix