I´d prefer a similar system like the one on Lebisey. The 2 flags on the top left unlock Chateau and the 2 flags top right unlock Windmill. So those 2 flags can be recaptured, while the US team have the option to attack another one.
I´m not a big friend of making flags not recappable., except some Maps that were designed for that. This sector push can make Maps really static.