The question is too vague.
What are the 2 classes?
No, not if the result of a schedule conflict. But again, it really depends on the classes she is opting for in lieu of honors precalc
Not having calc will probably not be an issue if she is realistic with her college list based on a 28-30 ACT. If you come back and say she is targeting Brown and Princeton, then she has greater challenges than not having calc.