Your math isn't accurate.
$367m: ESPN takes half
$183.5m: The ACC splits it up... ND gets an equal share of ACCN disbursement.
$12.23m: Annual increase ASSUMING absolutely zero league overhead and .... assuming every single Comcast subscriber in the country lives inside the ACC footprint and pays the in-state carriage rate. You'll find the out of market carriage cost to be a fraction of the in market cost. The red in this map represents Comcast:
So we'll keep on being insanely generous and say that you manage to get 2/3 of all Comcast subscribers in market.
You then arrive at your grand total of: $8m/yr/school
Now let's compare that shall we? ESPN just paid $300m/yr to buy out the CBS SEC package. That's $300m/yr .... to buy ONE FOOTBALL GAME per week. Add in the SEC offices taking a share so you divide by 17. That means each SEC school made $17.65m/yr/school just on that one football game a week. Comcast carriage gets doubled up on just with the CBS T1 game.
Back to my original point: Comcast doesn't move the needle. You need to realize gains more along the magnitude of $50m/yr/school to keep pace, especially after the Pac-12, B1G, and SEC all close open market new deals in the coming years.