if we're spending $11M on anyone, it's probably because we envision him improving enough that we can sell him for ($11 + X) million in a few years. No way that he would be a long term replacement for BWP. The long term replacement for BWP would be someone like Felipe - a good/great MLS player but one that won't move to Europe in a few years.
i don't think there is a team in the world that purchases young players thinking they won't be worth more than what they paid for them no matter how much the player originally costs.
And then regarding "long-term replacement" talk, if a DP gives me 3 years at a high level they can do whatever they want after. If you are signing a really good young DP and after 3 years no one in Europe is interested in him, he probably isn't good enough to spend decent coin on anyway or wasn't that successful here.