The ACC wouldn't go to divisions for standings and it's unlikely they'd standardize the schedule either. There's too many rivalries to protect. When/if the ACC goes to 18 games, you'll likely see an adaption of what they have now: permanent home-and-homes and rotating partners ranked by program strength.
http://graphics.fansonly.com/photos/schools/acc/sports/m-baskbl/auto_pdf/model-three-years.pdf
I predict each team will gain an extra home-and-home rival so the 18 games will feature 3 permanent home-and-homes, 4 roving home-and-homes, and 4 other conference games. Every other year, you'd have 2 chances at a team.
Perhaps the extra rivals will be:
BC - UMD (Northern pair, Gary Williams connection)
Clemson - UVA (Clemson - UNC or Wake would also work)
Duke - NC State (The triangle series is complete)
FSU - GATech (Recruiting and football rivals)
Miami - VATech (Old Big East teams get stuck together)
UNC - Wake (keeps NC teams happy that nearly all their state rivalries were kept in tact)