Hi @kelly1 ,
I am with @kmeeusen on this one, I have seen some incredibly large classes (in some cases a course where the entire institution is enrolled).
I would equally echo the biggest conundrum being the practical challenges that come with a course this large. Sections certainly helps, but the sheer management of a course with so many students can be cumbersome and could test the limits. I know the new gradebook has been specifically written to address some of the challenges faced previously with very large classes and difficulties that institutions faced.
Here in Australia we have courses that can have upwards of 2500 students, the largest we have so far in Canvas is 3000, however as our larger undergraduate courses are not on Canvas at this time we don't do any marking, grading or assignment submissions (as it is a Student Community).
I would be curious to hear more about your particular use case, how many students are you looking to enrol, and will it be for a graded course or more a community?
Cheers,
Stuart