I can't wait that EU citizen will hit them hard after May 25th.
Germany supposedly has some of the best privacy laws in the world. Their government freely abuses their people with domestic espionage. They'll continue to work with technology businesses to that end as it fits their purposes.
There's a lot of outrage about Facebook. Meanwhile, absolutely nothing has changed, or is going to change, about the NSA spying. Nothing got fixed. More or less the Snowden revelations were entirely meaningless in terms of changing the status quo. The NSA is spying on EU and US citizens just as they were five years ago, just as they will be five years from now. Where's the outrage today about the NSA? Almost everyone gave up, that's why Facebook is the new target, the people couldn't do anything about the government spying.
GDPR creates the haves and have nots when it comes to access to abuse privacy. That's all it will change. If you have the political access (which Palantir does and will), you're going to get the security keys to abuse privacy (the alternative is for EU governments to entirely shut down all domestic espionage, that will never happen).
The EU could stand up to the US if they felt it mattered.
Other than defence partnerships the EU is no more dependent on the US than the US is on the EU.
It's a two way street.
Unless you think the US would be happy to walk a way from the largest single market in the world (by GDP).
So the EU has teeth if the US pushed it too far.
It's hard to get the EU to agree on a lot of things but something sufficient to make the EU consider punishing the US would likely be important enough they would agree.