Announce end of support
It will be respectful if Asus will announce end of life for devices, I mean to say something like "guys, this is last update, don't expect anything else".
E.g. take a look on ZF6 subforum - obviously device is abandoned, despite having actual software, Asus doesn't want to update security patches. But users still expect something.
Lol, my old tablet on A10 has newer security patch.
Asus should take care more about customers, because these guys pay money for asus devices and with that attitude from company, next time they will think twice regarding which brand to select.