I doubt the 12.9" model will go up in price much since the display size on that one is the same, it will just have a smaller footprint. They're also using the newer LCD tech found in the iPhone XR but also have the cheaper aluminum frame. I'd bet that the price goes up $50-100, similar to the XR. It might also depend on whether it gets the wide camera from the iPhone X/8 or the newer one in the XS/XR. I'd also guess a higher price if they go to @3X retina which is basically 4K, but there doesn't seem to be evidence of that yet and I'm not sure if they can crank ProMotion 120Hz at that resolution yet. But with the display sizes coming closer together, I'm going to guess $749 for the 10.5" ($100 more) and $849 ($50 more) for the 12.9". They've done the same thing with the XS separating them by $100 and it used to be $120 for a while.
I also kinda wonder if we'll see a similar treatment to the 9.7" iPad—probably not this Spring, but maybe a year after that. They could use that new LCD tech and shrink the bezels around it and that would be the iPad Mini. Sure it wouldn't be as small as the old Mini but the footprint would be a good deal smaller and easier for children to hold. Or likely just kill the Mini name and this will be the spirit of it living on in a shrunken 9.7" casing, which is more spaced out now from the 11" than it was from the 10.5". It will also probably get a price bump up to $399 when they do that, with education pricing at $349.
I also kinda wonder if we'll see a similar treatment to the 9.7" iPad—probably not this Spring, but maybe a year after that. They could use that new LCD tech and shrink the bezels around it and that would be the iPad Mini. Sure it wouldn't be as small as the old Mini but the footprint would be a good deal smaller and easier for children to hold. Or likely just kill the Mini name and this will be the spirit of it living on in a shrunken 9.7" casing, which is more spaced out now from the 11" than it was from the 10.5". It will also probably get a price bump up to $399 when they do that, with education pricing at $349.