It doesn't really matter. They have other, legal, ways to get that information. It just takes them more time, effort and the oversight of a judge so they do it the easy way and violate peoples rights.
So if it becomes illegal for US agencies to gather this info, then Britain, Canada, New Zeeland, or Australia will gather the info and share it with the US. And we will return the favor.
The US agencies will still gather and share all that information amongst all those countries. This is about whether they can use the information "inadvertently" gathered about US citizens.
