Regarding the useful life of NAND Flash

[MaxMouseDLL]

Over the course of the years I've been around at MC, the question of NAND shelf life has been raised a couple of times, and no one has a definitive answer, until now. Hack a day set about systematically destroying a flash memory device via read/write cycles alone, now I know this flash memory probably isn't the same as the NAND contained within the PSP, but it's a pretty accurate analogue, here's what hack a day have to say on the subject:

The Flash_Destroyer finally succeeded in rewriting that EEPROM until its demise. When we originally looked at the device it had already recorded 2.5 million successful rewrites. The first appearance of corrupt data occurred at 11,494,069 but that doesn’t tell the whole story. The chip kept working for another 200,000 rewrites before finally showing repeated data corruption.
We do find the writeup pretty interesting. There’s one thing that we can’t stop coming back to though. In the discussion of our original article [Tiago] pointed out that long-term data retention isn’t being tested here. If the abuse of that EEPROM had ended after say five million rewrites, would it have been able to hold the data long-term without corruption?

It would seem that you're safe for at least 10,000,000 read/write cycles of your flash storage device, before corruption occurs, and as we know, the PSP contains extra blocks which it can use in the event of a permanent corruption (At least for most blocks, some are critical), so the useful shelf life of a PSP's NAND as a whole, is probably in the region of 10,000,000 ~ 20,000,000 read/write cycles.