This is the rub.
If Mariner promotes these players, he essentially makes himself obsolete. While some of us theorize that the Academy playing one way and the first team playing another will somehow magically result in a smooth transition to the first team these miss some major points.
1) The more players and coaches he brings in that can nurture the Klinsmann model, the less important he becomes
2) The players he needs to bring in to support his system are not the same ones that can excel under the Klinsmann model.
3) Beach Red makes a great point, attracting players here will be a challenge. Plata already left because he felt he couldn't develop under Mariner. If you are a US player, with USMNT aspirations, and the USMNT is playing 4-3-3, are you going to want to come here and wait for the transition to 4-3-3? If the transition is on again, are you going to want to lose again?
4) Let's assume that they decide in 2013 to play 4-3-3, are we purging the roster? Players that can play Mariner's system are on multi-year deals. A player like Dunfield is on the roster until his contract expires or he is waived. Either way, the flexibility to overhaul a roster over night is severely limited
For those reasons and many others, Academies and First Teams are learning the same system, at the same time. It's sort of being half-way pregnant. You are either on board or not. There really is no seamless middle ground