Asus generally supports it's phones for 2yrs (basically two major android upgrades)
Zenfone 3 got 2 major updates(Marshmallow to Nougat then Nougat to Oreo) and 2yrs of security patches (Asus gave what they promised)
It's highly unlikely it'll get any update/software patches now
But personally I think they should atleast provide 3major android updates + patches (like one plus does)
But still let's consider the fact that almost every OEM (all the major ones ) provide two major updates only (one plus is a exception here)
Asus as a smartphone OEM really transformed in 2019 they for the first time are taking their mobile division seriously (two innovative smartphones like Zenfone 6 and top of the class Rog 2 proves that also their update cycle really improved)
Hope if not 3 major android updates atleast 2+yrs of patches would be appreciated
I own a 5z looking forward to the Zenfone 7,Its one of the phones I'm considering upgrading to in 2020.
Cheers 😄