I see it the other way around the senior engineer is expensive and costs a lot 2 juniors are cheap. Who cares if their code is crap they produce it really fast so they find a bug, just fix it quickly. If anything the time a Sr. spends thinking about things to do things "right" is seen as a waste of time. Whereas the jr. will produce an enormous amount of buggy code but they can fix the bugs quickly by just throwing another prompt to ChatGPT to solve.
Now some might say that the code will be terrible quality and buggy and full of holes and the users will hate it, it is never economically viable to build enormous systems on a house of cards like that. To which I respond, you just described every piece of enterprise software I've ever used ever.