I did read an article by someone in the IT sphere who pointed out that all of the agreements the EU and UK (and indeed rest of the world) have with the US on protecting software could be thrown in the bin. For example, there isn't a rival to the Apple Store because of trading contracts between the US and other countries which specifically prohibits altering software.
If they are no longer an Ally, we could just start altering their software. It could be a huge development opportunity as Apple, Google, Microsoft - all of them would lose their protections around the world if Trump were kicked out of NATO or left NATO.
I can't find the article now, but that was the gist.