IMO what killed support on the older Nexus phones was /mostly/ the insufficient entry level storage.
This is provably false. The Nexus 6 plenty of storage space (32GB or 64GB) and does not get Oreo. Google's Nexus policy is to provide security updates for 3 years (or 18 months after the device stops selling, whichever is longer):
I thought the reason is Qualcomm not giving what it takes to support a newer firmware on their soc. I have a Nexus 5 on lineage and I'm on Linux kernel 3.4.0.
This is provably false. The Nexus 6 plenty of storage space (32GB or 64GB) and does not get Oreo. Google's Nexus policy is to provide security updates for 3 years (or 18 months after the device stops selling, whichever is longer):
https://www.theregister.co.uk/2017/05/01/google_eol_for_nexu...
Also, the average Android app size is smaller:
https://sweetpricing.com/blog/2017/02/average-app-file-size/