At least we're finally getting 2GB of RAM, which means the iPhone 6S will probably also get that. Will be interesting to see if that actually helps tab and app reloading issues, or if it's just iOS being buggy. I have a feeling they might still limit apps to 1GB and introduce split-screen multitasking, and the 2GB would only be for that. In the past the X usually stood for having a graphics chip with more cores to handle the retina display on the iPad over the smaller retina display on the iPhone. So this makes me think the iPad Air might get @3X retina similar to the iPhone 6 Plus. This also makes me think the iPad Mini will probably stay at 1GB of RAM, and either keep the A7 and see a price drop, or get an A8 (not X because the resolution would stay the same).
It's already ridiculous to start phones at 16GB, especially given how many people have skipped iOS 8 because they don't have enough storage space. But to keep a tablet at 16GB is ludicrous as more people use it for productivity. Many average users just buy the cheapest and don't realize they're going to burn through that space in a matter of weeks (like my mom and grandpa, even though I warned them). I agree that the second tier will probably be 64GB. But will they upgrade the 128GB to 256GB? They might hold off on that, or save that option for the iPad Pro next year.