Personally (and probably naively), I do hope the EU and US can find enough common ground. It'll make everyone's lives a lot easier [1].
[1] ...if the US can get out of the habit of rifling through the data of EU citizens at the drop of a hat.
I think this would pretty much only be a net loss for EU consumers and businesses. Maybe no longer having access to American tech companies' services would be beneficial long-term but only if EU entrepreneurs build domestic alternatives, which we know is pretty unlikely. I think the reality is that they'll just loosen their laws so they don't get shut out. As we're seeing them do here.
Why is it unlikely?
They won't. They have made it pretty clear that all your data are belong to us.
Maybe? I think that depends on how you're measuring "loss".