UEFA just imposed the so-called "home-grown rule", which forced Champion League teams to have at least eight home-grown players. At least four must have been produced by their own academy, the other can be graduates from other local academy. This is a version of imposing nationality requirement. Under EU ruling, workers (including footballers) from EU member countries are treated as locals. So it will be illegal for UEFA or local FAs to force clubs to have a certain number of local players.
This article, and the related discussion thread, reminds me on the classical free trade vs. protection debate. Free traders argue that protection will reduce overall competitiveness. The other side of the camp argue that some kind of protection will serve as incentives for local business (clubs) to invest more.
In the case of football, I must say, both camps have valid arguments. However, we can not assess the impact now - maybe in two World Cups. Historical data doesn't help provide conclusion as there are mixed results. Italy's youth development system is pretty solid, and it is translated to the national team's achievement. The Netherlands also have a good system (Ajax and PSV are well-known as producers of young talents), but they never won any World Cup (I know, the won the 1988 and 1996 Euros). On the other hand, Brazil and Argentina's system are not better than the Europeans, but they have abundant skilled talents to guarantee the national teams always perform well. Same thing can be said for France.
If we talk specifically about England, well, the problem lies on the input. The average talents of children entering the football academy (at the age of 10-12) is poor, according to an article I once read. I don't know what the reason is. This just illustrates that such 'home-grown' protection may not help countries like England much.
In other words, protection doesn't necessarily help a country in globalization.