I've got two Americans I can build around, and I'll try and sell the foreigner jerks. A couple of them have some crazy TPEs right now, so this could be as good a time as any.
Yes, the market is pretty high right now so your guys should sell for a decent amount, but keep in mind that also means the players you need to buy will be expensive as well. The switch was something I did one player at a time. Found a suitable American replacement for a foreign guy, bought one and sold the other. It was a little bit of a process, but I was able to keep winning while doing it so it worked well for me.
I consider the NT a distant 3rd for reasons to train
I forgot my ranked list for training at home, but I would agree that training for the NT isn't a huge reason that I train. Primarily because its so hard to train for.
Its very hard to get a 18 yo and train him up from start to finish to be in the NT either because:
1: You are in a low division and eventually his salary will grow monstrous and you can't afford him.
2: You are in a high division and can't really be competitive whilst training 18-21 year olds.
3: It requires a lot of money to buy one of these stud trainees (Ironically sometimes the same or larger amount of money than you would get for him if he was fully trained.
So it usually happens that one team trains the player in his early years and has to sell him to someone else who can afford the salary. This formula breaks the initial "bond" that you have with your 18 year old player. You can't say "Look at how good I trained this guy, because he was crap when I got him" because he was already trained and actually pretty decent when you got him. The "bond" between your 18 year old is there because you know how much he sucked when you got him and now he is actually a good player.