Look, here's the problem with the question, and it doesn't matter who asked it --
For decades, Apple's pricing of upgraded hardware has followed just one pattern: "about the same as the old hardware".
Price increases have happened, but only when hardware changes were significant enough -- like when the iPad Pro or iPhone 6 Plus were introduced. Outgoing hardware* has simply disappeared from the lineup, helped greatly by Tim Cook's expert control of the supply chain (you have to go back to the early 1990's to hear about aging stocks of unsold Apple desktops gathering dust).
If people have been watching Apple since, oh, 2014, they would see the same thing. New stuff gets announced, it's faster and better, and costs just as much as the old stuff; and the old stuff may, at best, appear in the "refurbished" section.
*The iPhone, and some iPads, are a rare exception. But, again, all the other products—don't forget that Apple makes computers and MP3 players, too—the old ones simply disappear.