At Kent, if you fail two classes in one academic year, you will be dismissed. Academic year for first year = Fall, spring, summer semester. If you fail one class, you remediate it in the summer. If you fail the remediation, it counts as two failures and you are dismissed (you can appeal to be readmitted for the class below you). You would then come back when it's time to take the class you had failed with the new class (if you were dismissed and readmitted). If you pass, you continue on after the remediation. If you fail one class and successfully remediate it in the summer, you just continue on with your current class. If you failed another class after that remediation, it would be in the next academic year-- you would have to remediate it in the following summer. It's always best not to fail a class obviously, but it happens. There are people that had to remediate and are doing just fine now. There is also a six year limit on getting through the program.
My first year, we lost a few people. In second year, we had a few join our class from the class above us (readmitted students). There are a lot of tutoring services, people to help, etc., but you have to make the effort to ask for help & actually put in the hard work. As @DexterMorganSK said, programs do try to keep their students from day 1.