They are maintaining those conferences but that doesn't mean the teams in them will stay the same as now. It also doesn't mean those will be the only conferences (70 teams in 4 conferences would be 17.5 teams per conference, 5 conferences is a perfect 14 pet conference).
Most importantly you have to consider the "Why?" behind teams like USC, Oregon, UCLA, Washington going all the way over to the B1G. It was money!
That reason would no longer exist under this plan and with all of these teams under the same League (not called the NCAA) the money remains same regardless of their conferences and they could have freedom to easily realign the teams to their regional conferences.
Example: B1G has 18 teams and would need to move to 14. 4 Pac teams return to Pac/Western Conference (not sure about rights regarding the naming of it), Nebraska goes back to Big 12 and ND makes long anticipated move to B1G.
This same type of thing would happen with the other conferences, like the SEC currently has 16 teams, so they could slide TX, A&M, and OU back to the Big 12 and add, say FSU since bridges seem burnt between them and the ACC.