Maybe, maybe not. Apple tends to incorporate the features it wants into its hardware early on, but may not expose it in the OS until it's ready to expose it.
One example of this was HEVC support in the iPhone 6 with A8. They did actually expose it in FaceTime and then suddenly stopped talking about it, and I wonder if it was because of licensing issues. Then they reintroduced it with A9, but not until years later. A9 was introduced in 2015, but HEVC support on A9 wasn't introduced until 2017.
It will work great with the existing models. However, I'd say there is a 99% chance the current Magic Keyboard won't fit the OLED iPad Pro.
What? That doesn't look like that to me. The speaker grills remain on the short sides, where they should be for landscape mode.