Likelihood of rescinded offer?

I was offered admission to the faculty of Engineering (MechE, CivilE), described as “Admitted Pending Final Results”. I’m a US high school student in the IB program, and the only concrete requirements they ask for are the US diploma and the IB diploma.

Other than missing those, how possible/common is it for offers of admission to be rescinded for lower senior grades? I got 6 As and 1 B first semester of senior year (submitted before admission decision), and as a worst case scenario, I could imagine myself getting 4-5 Bs and 1-2 As this semester. Is this likely to be a problem, or does McGill worry more about grades below a B? (I know McGill doesn’t really take that into account, but all but one of my classes are IB courses, 4/5 of which are at the higher level)

Thanks!

The mantra is no D’s, no F’s and no felonies.

@TomSrOfBoston thanks for your response!

McGill also seems unusual in that they admit pending a successful IB diploma, despite stating that they don’t base admissions decisions on IB courses/diploma (for US students)