The P4 here is already on pretty shaky ground when it comes to plausibility, and the G4 is significantly more shaky, but here's an 8x16 future scenario:

ACC
East: Duke, NC State, North Carolina, Wake Forest
North: Boston College, Notre Dame, Pittsburgh, Syracuse
South: Florida State, Miami-FL, Virginia, Virginia Tech
West: Cincinnati, Clemson, Georgia Tech, Louisville

Big Ten
East: Maryland, Ohio State, Penn State, Rutgers
North: Indiana, Michigan, Michigan State, Purdue
South: Illinois, Kansas, Missouri, Nebraska
West: Iowa, Minnesota, Northwestern, Wisconsin

Pac-16
East: Houston, TCU, Texas, Texas Tech
North: Oregon, Oregon State, Washington, Washington State
South: Arizona, Arizona State, Colorado, Utah
West: California, Stanford, UCLA, USC

SEC
East: Florida, Georgia, South Carolina, West Virginia
North: Arkansas, Kentucky, Tennessee, Vanderbilt
South: Alabama, Auburn, Mississippi State, Ole Miss
West: LSU, Oklahoma, Oklahoma State, Texas A&M

American
East: Army*, Connecticut, Navy*, Temple
North: Iowa State, Kansas State, Memphis, Tulsa
South: Central Florida, East Carolina, South Florida, Tulane
West: Baylor, BYU*, Rice, SMU

MAC
East: Akron, Buffalo, Kent State, Massachusetts*
North: Central Michigan, Eastern Michigan, Northern Illinois, Western Michigan
South: Ball State, Marshall, Middle Tennessee, Western Kentucky
West: Bowling Green, Miami-OH, Ohio, Toledo

MWC
East: Air Force, Colorado State, New Mexico, Wyoming
North: Boise State, Nevada, UNLV, Utah State
South: North Texas, Texas State, UTEP, UTSA
West: Fresno State, Hawaii*, San Diego State, San Jose State

Sun Belt
East: FAU, FIU, Georgia Southern, Georgia State
North: Appalachian State, Charlotte, Coastal Carolina, Old Dominion
South: South Alabama, Southern Miss, Troy, UAB
West: Arkansas State, Louisiana Tech, Louisiana-Lafayette, Louisiana-Monroe