Hi cn1ght,
Latex is generally the most durable of all the foam materials but softness is a durability factor in all materials … including latex. There is more in post #4 here about the many variables that can affect durability and the useful life of a mattress. Some latex manufacturers won’t sell the softest versions of latex because potential durability issues with some people (and the potential risk of alignment issues). Durability is also relative to each person because if you are close to the edge of the softness range that would be suitable for you in terms of PPP then only a very small amount of softening may put you outside of your suitable range and for you the mattress would be too soft even though the materials may have only softened a small amount and would still be fine for someone else (see post #2 here).
Phoenix