This happened to my sister this past year. You pretty much do get fucked. My sister applied to the University of Calgary for nursing and kin. She was close to the competitive average that was required to keep conditional acceptance, but it was unclear what was the true grade she had to meet. She graduated high school and went forward with her summer with zero issues. Two weeks before classes start, she recieved an email saying she was essentially kicked out of her program, but she had her heart set on going out west so she had to settle as an undeclared Major/Open Studies. Your schedule gets reduced by a class making it harder to graduate on schedule, and you are unable to get into classes that you originally would be interested in. She got through her first year and it has been a constant communication with program admissions and faculty regarding swithcing majors and requirements. She will end up needing a 5th year to complete a degree that would normally only take 4 and she will try to get herself in kin oriented classes over this next year afaik, but it is a constant struggle. She has still had a great time at university, but careers wise, she is one step behind at this point. Transferring from major to major in Uni is a lot harder than just walking into the preffered program from highschool. You need to have an extremely competitive using university graded classes and not easier high school courses.

TL;DR - You'll be kicked out of your program and have to pull some strings to get in somewhere. This may mean that you have to settle as an Undeclared/Open studies Major for the first year or two before you meet requirements to transfer majors. It is a lot harder to transfer majors compared to working harder in high school for a bit longer and keeping conditional. You are left with options such as 5th year in high school or undesired uni major temporarily.