I was reading threads on here about schools who are very large who are not at the highest level with or without football. I break this down into 4 groups.
Group 1:30,000 and above enrollments.
Group 2:20,000 to 29,999 enrollment.
Group 3:10,000 to 19,999 enrollment.
Group 4:6000 to 9,999 enrollment of private and any public schools that could hit 10,000 enrollment mark in a few years.

Group 1:30,000 +
Wichita State AAC
British Columbia NAIA and USport
UTA SBC
Kennesaw State A-Sun
George Mason A-10
VCU A10
Fullerton State Big West
Northridge State Big West
Long Beach State big West
UC-Dais Big West/Big Sky
UC-Irvine Big West
UC-San Diego Big West
IUPUI Horizon
Milwaukee Horizon
Illinois-Chicago Horizon
Grand Canyon U. WAC
UTRGV WAC
Utah Valley WAC
San Francisco State D2
NYU D3
Toronto USport

Group 2:
Northern Arizona Big Sky
Portland State big Sky
Sacramento State Big Sky
Weber State Big Sky
Delaware CAA
Drexel CAA
James Madison CAA
Northeastern CAA
Towson CAA
Columbia Ivy
Cornell Ivy
Harvard Ivy
Penn. Ivy
Illinois State MVFC
Missouri State MVFC
Stony Brook CAA/A10
George Washington A10
DePaul Big East
St. John's, NY Big East
Cal. Poly SLO Big Sky/Big West
UC-Riverside Big West
UC-Santa Barbara Big West
Oakland Horizon
Sam Houston State
Cal. Poly-Pomona D2
CSU-L.A. D2
Grand Valley State D2
Wayne State, Mich. D2 Could reach 30,000 in a few years.
Metro State D2
Nova Southeastern D2
UT-Dallas D3 Looking to make a move to D2.
Johns Hopkins D3
Hunter D3

Group 3:
Little Rock SBC
Eastern Washington Big Sky
Idaho Big Sky
Idaho State Big Sky
Montana Big Sky
Montana State Big Sky
Northern Colorado Big Sky
College of Charleston CAA
Hofstra CAA
UNC-Wilmington CAA
Yale Ivy
Howard MEAC
Florida A&M MEAC
North Carolina A&T MEAC
North Carolina Central MEAC
Northern Iowa MVFC
South Dakota MVFC
Indiana State MVFC
North Dakota State MVFC
South Dakota State MVFC
Southern Illinois MVFC
Western Illinois MVFC
Youngstown State MVFC
Central Connecticut State NEC
LIU NEC
Austin Peay State OVC
Eastern Kentucky OVC
Morehead State OVC
Murray State OVC
SE Missouri State OVC
Southern Illinois-Edwardsille OVC
Tennessee Tech OVC
Tennessee State OVC
Boston U. Patriot
Dayton A10
Chattanooga Southern
East Tennessee State Southern
UNC-Greensboro Southern
Western Carolina Southern
Central Arkansas
Incarnate Word
Lamar
SE Louisiana
SFA
Texas A&M-Corpus Christie
Jackson State SWAC
Prairie View SWAC
Texas Southern SWAC
Albany CAA/AEC
Binghamton AEC
Maine CAA/AEC
UMBC AEC
UMass.-Lowell AEC
New Hampshire CAA/AEC
Vermont AEC
FGCU ASun
NJIT ASun
North Florida ASun
Duquense A10
Fordham A10
URI A10
Saint Louis A10
Georgetown Big East/Patriot
Marquette Big East
Villinova Big East/CAA
Cleveland State Horizon
Northern Kentucky Horizon
Wright State Horizon
Loyola-Chicago MVC
Denver Summit
Omaha Summit
PUFW Summit
San Francisco WCC
UMKC WAC
Chico State D2
CSU-Dominguez Hills D2
CSU-East Bay D2
CSU-San Bernardino D2
CSU-San Marcos D2
Mercy D2
NY Tech D2 sports have been suspended for a short period. Not sure why yet.
Queens D2
Arkansas Tech D2
Davenport D2
Ferris State D2
Purdue NW D2
Alaska-Anchorage D2
Central Washington D2
Western Washington D2
Valdosta State D2
West Florida D2
West Georgia D2
Angelo State D2
Tarleton State D2
Texas A&M-Commerce D2
Texas Women's D2
West Texas A&M D2
Central Missouri D2
Central Oklahoma D2
Fort Hays State D2
Pace D2
Southern Conn. State D2
Southern New Hampshire D2
Minn. State-Mankato D2
Minn.-Duluth D2
St. Cloud State D2
Academy of Art D2
North Georgia D2
Indiana, Pa. D2
Kutztown D2
West Chester D2
Colorado Mesa D2
Colorado-Colorado Springs D2
Dixie State D2
Buruch D3
CCNY D3
John Jay Criminal of Law D3
Lehman D3
Brooklyn D3'
Staten Island D3
Johnson and Wales D3
Suffolk D3
UC-Santa Cruz D3
RIT
UMass.-Boston
Southern Maine
MIT
Montclair State
Rutgers-Newark
William Paterson
Kean
Rowan
Buffalo State
Carnegie Mellon
Case Western Resere
Emory
U. of Chicago
Washington, Mo.
Wis-Eau Claire
Wis.-Oshkosh
Wis.Whitewater
Indiana Wesleyan NAIA
Bellevue NAIA
Victoria NAIa/USport
Savannah College of Art and Design NAIA

Group 4:
Campbell Big South
Radford
Elon CAA
Brown
Dartmouth
Princeton
FDU
Sacred Heart
Belmont
Jacksonville State
American U.
Jacksonville
Marist
Mercer
Hartdford
La Salle
Richmond
St. Joseph's, PA.
Creighton
Seton Hall
Xavier
CSU-Bakersfield
Monmouth, NJ.
Quinnipiac
McNeese State
New Orleans
NW Louisiana State
Gonzaga
Loyola Marymount
Pacific
Pepperdine
San Diego
Santa Clara
California Baptist
Seattle U.
CSU-Stanislous (sp) D2
Post U.
Harding
Ashland
Saginaw Valley
Lewis U.
S. Indiana
Truman State
Alaska
Western Oregon
UAH
Texas A&M-Kingsville
Lindenwood
NE Oklahoma State
Washburn
Adelphi
New Haven
U. Iowa
Azusa Pacific
Hawaii Pacific
Augusta
Columbus State
Bloomsburg
California, PA.
Edinboro
Millersville
Shippensburg
Slippery Rock
Regis
Barry
Emory Riddle-Florida
Florida Tech
Tampa
Salisbury
U. of New England D3
New Rochelle
Ithaca
Rhode Island College
UMass.-Dartmouth
Widener
St. Thomas Minn.
Lesley
Farmingdale State
Yeshiva
Chapman
SUNY-New Paltz
SUNY-Oswego
Rochester
Wis.-La Crosse
Wis.-Stevens Point
Wis.-Stout
UC-Merced
S. Oregon NAIA
Governors State
Indiana-South Bend
Roosevelt
Georgia Gwinnett
Middle Georgia State
Mich.-Dearborn

As we look at this list, the schools with more than 30,000 students might be able to support an FBS football team. When schools like the Big West schools dropped football? They did not have the students enrolled at the time to support football like they do today. Some of the schools could use stadiums close by.
CSU-Domiguez Hills do hae an on campus stadium that was built for soccer. The cash to built the stadium was helped by the donations from the city and from the pro-soccer team that went there. Several schools on this list have been looking at adding football. UNF could use the pro stadium in Jacksonville.

Which schools on this list looks good to expand with? I say Wayne State Michigan to the Horizon looks like a perfect fit. They could park their football in MVFC with Youngstown State.