Flash and NAND are more or less the same, so in the instances where flash is vulnerable, NAND also is, I think.It's flash rather than NAND. The PS4 has three distinct banks of RAM: 8Gb GDDR5 (using Samsung K4G41325FC-HC03 chips), 2Gb DDR3 (a Samsung K4B2G1646E-BCK0 chip), 256mb Flash (a Macronix MX25L25635FMI chip).
That limit the number of updates a system can get, I suppose. Or is the fuse just disabled and can be enabled again later?