It would be nice if the youth team would be tied to the main one in terms of passage of players from one to the other. The youth one would draft the guys and every season could transfert for free three of them to the main one, those who the owner consider well trained and ready. The youth team would play in a youth tournament. Every main team should have a youth one for free. No more drafted guys in the main teams, no more forced training playing games with a young guy in 48 minutes position that will let you loose the game. The only training in the main team could be about ready players to be finished. I guess there's should be a limit of 23 yo to keep a player in a young team (but they could be transferred in the main one earlier or sold if the owner wants it) and than the guy should be sold if he's not in the plans of the manager or fired if there's no interest (with the FA rules eventually applied).
Economy should be separated between the two teams.
Not what I propose, but I like it a lot. Solving the problem with training and making the games more competitive.
I'm afraid it's too many changes for the BB's to like it.
I don't know if we will get a mobile app, but I can see more people getting hook up to the game with a youth team, no matter what way they implement it.