Batteries don't last that long still, last I heard you get about 1000 charges before you need to do serious maintenance to a phone, in which case you'll probably want the latest and greatest anyhow.
Why, if it still works fine?
//Nexus 7 (2012) user here
I have a moto g3 quadcore and 1G(maybe 2G)RAM. I cannot reason about slow performance for non gaming / pixel heavy stuff.
I also have a first generation Moto G (~2014) and an app I have here (OS Monitor) reports 70% battery health. In practical terms, the battery lasts a day of normal usage.
On the other hand, I have a ~2 year old Toshiba, and Linux here is reporting 0% battery health and a "last full capacity" of 0 mAh. If I unplug it, it goes under in 5-10 minutes (factory battery life was about 2:30 hours).
I read that the biggest battery killer is heat, not charge/discharge cycles.
Regardless, and if I am not mistaken, that figure of 1000 charge cycles is for cycles of 100% discharge (or as close as you can get before the protection circuits cut in) followed by 100% charge. This rarely happens in the "real world" and thus that figure will probably be much higher when adjusted for real world conditions.
It still works fine, although I do use Firefox with ad-blocking extensions. I doubt I'll need to replace it for at least another year.
https://i.imgur.com/9dnRrA0.jpg
When I bought the extended battery kit it lasted from 3-5 days. 3 major Android releases later it is rivaling some dumbphones.
Not having to worry ever about battery life has been life-changing and I'm not going back.