Flash limits
"the limits Flash places on the number of times a given memory cell can be written to"
AFAIK, they're up to 1m+ rewrites per cell if it's based on NAND cells. I also recall seeing details released about the drives that says they incorporate algorithms to spread out the re-writes across the drive to save this becoming a problem in the short to medium term.
Coupled with the fact that no-one should be relying on a single drive I doubt there's that big of a problem.