NBC has paid huge money for Premier League rights and while they can continue broadcasting Saturday morning matches, picking up more CFB will limit their ability to show games mid-day or in the early afternoon. I’m not sure what the difference is between a B12 game or a Premier League match on network TV, but that last audience is a growing one. NBC would seem to have the ability to do 2 CFB games daily while still fulfilling that whole Premier League contract - they could do a 3-3:30pm kick and then a late game. So there is an opening for the B12 there, but it would likely only be for 1 game at least on Saturdays, and times would certainly be secondary to whatever Notre Dame wants.
Last fall's PL broadcast (non-streaming) schedule, with ND games added:
all times Eastern
Sat 9/11 - 10am (USA), 12:30 (NBC),
2:30 Notre Dame (Peacock only)
Sat 9/18 - 10am (USA), 12:30 (NBC),
2:30 Notre Dame
Sat 9/25 - 10am (NBCSN), 12:30 (NBCSN)
Sat 10/2 - 12:30 (NBC),
2:30 Notre Dame
Sat 10/16 - 10am (USA), 12:30 (NBC)
Sat 10/23 - 10am (USA), 12:30 (NBC),
7:30 Notre Dame
Sat 10/30 - 10am (USA), 12:30 (NBC),
7:30 Notre Dame
Sat 11/6 - 1:30 (NBC),
3:30 Notre Dame
Sat 11/20 - 10am (USA), 12:30 (NBC),
2:30 Notre Dame
If NBC keeps a similar scheduling model with PL, you could possibly have any combination of:
*12:00/12:30ET CFB on USA
*2:30ET Notre Dame
*6:00/6:30ET (4:00/4:30MT) CFB on NBC, which would leave at least an hour for primetime network programming, followed by news and SNL.
*7:00ET (5:00MT) CFB on USA