The thing is no coach in their right state of mind would risk taking their B side half-way around the planet and risk jeopardizing their chances of going to the WC.
What might be happening right now (not just for us) is NT coaches sweetening the deal with clubs by releasing players early if at all possible.
Come play off time, every single team will have their best team out there for the first leg. A resounding victory may potentially result in players being released early (a-la Chris Wood and Ryan Thomas), although they will need to be 100% certain of qualifying or risk getting skinned alive if they don't.
Last World Cup it was Uruguay vs. Jordan in the CONMEBOL - AFC Inter-Continental Play-off.
Uruguay fielded their strongest eleven in both legs, starting the second leg at home with the same eleven as started away a week before.
Despite having won 5-0 away.
Somewhat surprisingly the second leg was a 0-0 draw.
This is the Uruguay side that started the first leg away in Jordan:
Uruguay: Martin Silva, Maxi Pereira, Lugano, Godin, Caceres, Arevalo Rios, Rodriguez, Lodeiro (Pereira 70), Stuani (Ramirez 70), Cavani, Suarez (Forlan 81).
Subs Not Used: Castillo, Fucile, Gargano, Gimenez, Hernandez, Perez, Scotti, Gonzalez, Munoz.
Goals: Maxi Pereira 16, Stuani 42, Lodeiro 69, Rodriguez 78, Cavani 90
Seven days later, this was the side for the home leg in Montevideo (a 0-0 draw):
Uruguay: Martin Silva, M. Caceres, Lugano, Maxi. Pereira, Godin, Arevalo Rios, Lodeiro, Rodríguez, Stuani, Cavani, Suárez,
Substitutes On:
D. Forlán, G. Ramírez, A. Hernández
Substitutes Out:
Big Pete 65, Christchurch