when a model is discontinued, especially when it is discontinued so soon as the 9.7 Pro, it CAN impact the ownership experience. Companies stop making and selling accessories designed for it. Apple isn't selling the smart keyboard for it any more. The good news for 9.7 Pro owners is that it shares the same form factor as the Air 2 so there are still choices.
Resale value on the 9.7 Pro is NOT going to increase because it isn't more desirable than its replacement. The 10.5 Pro is only ever so slightly larger that it most likely not be a factor.