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?
Maybe? I think that depends on how you're measuring "loss".
They won't. They have made it pretty clear that all your data are belong to us.