It is a spec bump, but a huge one in terms of speed, and the 12.9" getting smaller and lighter is what I always wanted so that I can move to the larger size, which is going to be great. I think in iOS 13 Apple is going to take off the gloves and deliver a solid update for the iPad. I think they are on a tick-tock cycle with iOS now. One year is optimization with a few features, the next year is mainly features with a little optimization. iOS 11 was a fairly beefy upgrade for the iPad bringing more and better multitasking, the dock, the new app switcher, and the Files app, but I think iOS 13 is going to be even better.
I could see them doing more with the USB-C and opening it up more to developers, giving access to external drives in the Files app. They could also make the iPad turn into a keyboard with trackpad when connected to an external display and use a more advanced, kinda reverse version of Project Marzipan to display macOS "Lite" when docked to allow professional and built-in apps with mouse optimized interfaces on external displays, perhaps even wirelessly with Apple TV. They could also rework some of the interaction and input methods to be improved along with contextual input and modifiers when editing something. Another thing is rethinking windowing for the iPad. They could also allow more advanced background processing or provide APIs to monitor for certain events. Something like that would be really useful when I'm doing development work and have a build process in the background. They could bring Xcode to the iPad. They could provide some sort of a software clipboard/project files holder that you can swipe in and off the display when needed while moving between multiple apps. They could allow apps to be updated in the background when resources change in another app. They would mean they need an actual project workflow that isn't sandboxed to different apps but is a common area that you can define as a container for each project and that can be your working folder that all apps can share. That could be kept in sync with your Mac over iCloud or even over a local network for faster updates, with the option to plug in the USB-C cable to your Mac or someone else's and simply copy over whatever project folders you're working on or move a project from your Mac onto the iPad. It should be as seamless as possible between the iPad and Mac but it also needs to work both quickly and reliably. These are all big challenges and I think Apple has been trying to piece together exactly how to do it and this year they're building it behind closed doors. Hope I'm not wrong.
