I have the 2017 12.9 iPad Pro and I love it, just can’t justify upgrading as much as I want to. My strategy these days is to run my Apple devices until they stop getting support.
no need to upgrade when Apple doesn't give support anymore. My MBP Retina mid 2012 is not supported anymore. Ny Apple. Still can get parts for it though. Recently had to replace a fan, as it was fubar. A local shop (Apple approved reseller thing) ordered them , received them, replaced them. Same with the 4 rubber feet. Worn out/off after almost 8 years of happy duty ;-)
I might not be the pro some of you are, but this machine is still doing all I need, so yes, looking at the new 16" model, loving it etc, but why upgrade?
For sure not because getting support is stopped.
Use it until it really fails on you, and nothing can be done about it.