“I disagree. According to your rationale, the reason you cannot continue eating forever (as long as you haven’t made a ברכה אחרונה) is because the brocho is only chal when you eat it – so if you make a brocho on a large challah, and begin eating it, can you continue eating the challah without a new brocho tomorrow? Obviously not.”
I’m not sure what you are trying to say here. According to halacha, once you make a bracha you can continue eating all day unless something happens that is considered to be a “hefseik” according to halacha. A bracha achrona is one type of “hefseik”.
Going to sleep for the night is another type of “hefseik.” So even if you didn’t make a bracha achrona, you would not be allowed to continue eating the next day without a new bracha (assuming you went to sleep). “But you would be allowed to continue eating the entire day until you go to sleep (unless you do one of the other things that create a hefseik).
(Source: “Halachos of Brachos” by Rav Bodner, page 158-159): “Most Poskim rule, that, although a lapse of time affects a brocha achrona, it does not affect a brocha rishona….Since the brocha on nuts is valid for the entire day (provided that it is not terminated by a change of location, a decision to stop eating or the recital of a bracha achrona), he may continue eating nuts (or any other fruit that was included in his original brocha until the time he goes to sleep, without having to make a new brocha.”)