About now. The band of admitted students' credentials is pretty high and actually very narrow at BYU. And the Ivy students I knew had pretty good horsepower under the hood but a ton less motivation, drive, and work ethic than nearly all BYU students.
Finally, I think that if your aspiration is to be an Ivy clone, you are a) already too big because most Ivies are much smaller in undergraduate enrollment (my school had 8k undergrads); and b) too small in terms of grad programs and students (my school had 10k grad students and professional students). The only thing we might someday have is even more highly credentialed undergrads.
A better model is the giant state flagship school with great academics, like Texas, Michigan, Virginia, or even a private school like Notre Dame or Purdue for that matter, based on who we already are and are likely to continue to be.