Surely the Pro is more future proof for software updates due to:
"The biggest differences are in the RAM and CPU department. Apple has packed 4GB of RAM into the iPad Pro models–the most RAM Apple has ever used and TWICE as much as the 2GB of RAM found in the iPad Air 2. That extra RAM combined with the A9X processor found in the Pro models means these things will wipe the floor for the Air when it comes to processing power. Apple says the A9X chip has 1.8 times the CPU performance and 2 times the GPU performance of the A8X chip found in the Air."
"The biggest differences are in the RAM and CPU department. Apple has packed 4GB of RAM into the iPad Pro models–the most RAM Apple has ever used and TWICE as much as the 2GB of RAM found in the iPad Air 2. That extra RAM combined with the A9X processor found in the Pro models means these things will wipe the floor for the Air when it comes to processing power. Apple says the A9X chip has 1.8 times the CPU performance and 2 times the GPU performance of the A8X chip found in the Air."