Apple loves to have something for next years ’big thing’. Could just be their marketing strategy too. Getting people to buy more expensive 12.9. Reading some MR comments, it’s working.100% agree.
Never say never, but I'd be really surprised as well. IMO there is nothing to gain from Apple's perspective to up the display specs in the middle of a cycle. They'd rather wait for the next cycle which makes things simpler from them, won't alienate recent buyers as much, and might even be a reason for purchasers of this years model to upgrade to the next gen hone it comes out.