The Athletic had an article advocating for division-less football a few weeks ago, and here were their proposed ACC rivalries:
Boston College — Miami, Syracuse, Virginia Tech
Clemson — NC State, Georgia Tech, Florida State
Duke — North Carolina, Wake Forest, Syracuse
Florida State — Miami, Clemson, Georgia Tech
Georgia Tech — Clemson, Florida State, Louisville
Louisville — Pittsburgh, Virginia Tech, Georgia Tech
Miami — Florida State, Boston College, Pittsburgh
North Carolina — Duke, NC State, Virginia
NC State — Clemson, Wake Forest, North Carolina
Pittsburgh — Louisville, Miami, Syracuse
Syracuse — Boston College, ??, Pittsburgh
Virginia — Virginia Tech, North Carolina, Wake Forest
Virginia Tech — Virginia, Louisville, Boston College
Wake Forest — Duke, NC State, Virginia
I would prefer something like, though I won't be holding my breath:
Boston College — Miami, Syracuse, Virginia Tech
Clemson — Virginia, Georgia Tech, Florida State
Duke — North Carolina, Wake Forest, NC State
Florida State — Miami, Clemson, UVA
Georgia Tech — Clemson, Virginia Tech, Louisville
Louisville — Pittsburgh, Syracuse, Georgia Tech
Miami — Florida State, Boston College, Pittsburgh
North Carolina — Duke, NC State, Wake
NC State — Duke, Wake Forest, North Carolina
Pittsburgh — Louisville, Miami, Syracuse
Syracuse — Boston College, Louisville, Pittsburgh
Virginia — Virginia Tech, Clemson, Florida State
Virginia Tech — Virginia, Georgia Tech, Boston College
Wake Forest — Duke, NC State, UNC