But with the Big 10 expanding to 18 teams next year, how will all the different schools games be on streaming/cable/networks?
That's up to the league. They just signed a $7 billion rights deal. It likely has an escalator clause if they add more teams.
Big Ten completes 7-year, $7 billion media rights agreement with Fox, CBS, NBC
The Big Ten has completed a new seven-year media rights agreement with Fox, CBS and NBC that is set to bring in more than $7 billion to one of the nation's most powerful athletic conferences.
They also have their own network for overflow games. But TV is run by the league.