Originally Posted by TizzyT
Besides some hardware revisions the main reason that newer models can't downgrade is because of bootldr+metldr iirc. Those 2 are what defines the lowest firmware a system can go to.
PS: iirc the keytable is running out of space, if true Sony will eventually not be able to add new keys anymore at least not in the same way they have been doing.
I am not worried about Sony to find more way of allocating new page tables
bootldr and metldr might be the problem of downgrading with their latest patches, though it is intriguing to see if dumping the eid key is possible and then converting to dex and test new downgrades on dex firmwares.
But I guess the time consuming of writing new drivers to lower fws probably may not be worth it.
This is also why I think E3 was/is planning to make a mfw based on 3.60-3.73 ,probably 3.66 for minimal fw with full drivers support, to increase their flasher sales.