Strut mounts
 

At what point should someone plan on replacing them?

Looking at them I imagine the fronts for sure wear out but what about the rears?

Data point: when I took all my suspension apart for an ROW M030 upgrade at 70K, the front mounts were squeaky and a little worn, the rears were perfect. Lots of autocrosses. They're cheap parts, wait for strut replacements.

My rear strut mounts looked fine at 103K miles, but the redesigned 987 mounts have less rubber & more metal to secure the strut. The difference is very noticeable. :)