Consider that current rumors point towards no 11" model. Just 12.9".
I wouldn't consider that more than conjecture from some posters here, and should be accompanied by a Himalayan salt lamp. Apple isn't going to force users who don't want the larger size to forego the "Pro" features and settle for an Air 4, any more than it will stop offering the iPhones Pro in anything but the larger Max phablet size.
Now, the company may give the 12.9" extra features, such as mini-LED, or more RAM (as it has done in the past), but it's not going to leave money on the table by not offering an 11" Pro, when it outsells the larger model.
The aim is to incentivize up-sells without stepping over the line into forcing deeper compromises, as would be the case with the Air 4 as surrogate, or, penalizing users outright.
As for the OP's dilemma, I answered that myself and picked up a 11" Pro today at the local store, which can have stock, despite what Apple's website indicates. It succeeds an 64GB Air 1, which is still OK in most respects, and can even run iOS 12, but feeling its age when it comes to battery life and limited memory (both RAM and storage).
I had been waiting for the Air to make the leap to a modern form factor, and if the Air 4 had been offered with 128GB, it would have been a much easier choice. I've visited a couple stores recently, and based on the disclaimers personnel are giving about it not having arrived, there is a great deal of interest in the Air 4. Indicate you're interested in an iPad, and the first thing the store people will mention is that they don't have the Air yet.
But with the price of the 256GB model the same as the 128GB Pro's EDU, or sale pricing (as Amazon has been offering recently, as well as some resellers), the confluence of features of the Pro won out. For qualifying EDU buyers, the soon-to-expire free AirPods offer is the coup de grâce, to be enjoyed, or re-sold.
The A14 is a beast (which portends even better things for those who can wait for the A14X), but the only place where it opens a gap on the A12Z is in the single-core score. The more modern neural engine in the A14 is probably a leap as well, but that doesn't explicitly manifest itself in benchmarks. In other respects, the two are in the same ballpark.
Apple does a great deal of work on iOS' memory management, and the Air 4's 4GB RAM does provide a cushion over the current 3GB baseline in the value/mainstream products (SE2, iPad 8). But, ultimately, the support window in iOS devices has been heavily influenced more by memory than outright speed, so the 6GB in the Pro provides more cushion.
Otherwise, Face ID (albeit a subjective preference, YMMV), ProMotion screen (+brightness), dual-cameras w/flash +LiDAR, quad-speakers, and five microphones are additional features I was willing to trade for the extra storage. 64GB a bit too constricting, 256GB more than enough, but 128GB just right. Learned that lesson with my 64GB XS, and didn't want to encounter that situation again. More nits can be picked in terms of the narrower bezels, and 18 vs 20W adapter, but they are very minor in my book.
So, for me, for today, the 11" Pro is a better overall package, if one can't manage with the base 64GB Air 4. The EDU promo with the AirPods made it a no brainer.
Apple's product planners about as good as they get in terms of up-sells, and they've found another victim.