I do not think BYU would join a league like the Valley where they would feel obligated to remain long-term.
This is all positioning, IMO, to be the instigator for a new entity out West.
I suggested this could be a future 12-member football league after the future dissolution of the BXII:
East
Iowa State
Kansas
Kansas State
Memphis
Texas Tech
Tulsa
West
Air Force
Boise State
BYU
Colorado State
New Mexico
UNLV
My addition to the above would be Bradley and Creighton partnering with DePaul and Marquette to create a block of 4 to make that a 16-team hoops league with the following divisions:
East "Naismith" Division
Bradley
Creighton
DePaul
Iowa State
Kansas
Kansas State
Marquette
Memphis
West "Tarkanian" Division
Air Force
Boise State
BYU
Colorado State
New Mexico
Texas Tech
Tulsa
UNLV