If the 11" didn’t tip the scales, a speed-bumped model this fall probably might not either. You’ll have to see how much faster it is, and whether than means enough to you.
According to Kuo one internal difference in the year-end model will allow the antenna to connect directly to the motherboard, “which will supposedly help reduce signal loss and improve overall networking performance,” according to Appleinsider.
The late 2020 (or possibly early 2021) model should be a big jump from your 10.5" though, with improved performance, image, and battery life.