A possible retaliation by the EU could be to not enforce US intellectual property rights in the EU anymore. Or we could start taxing cloud companies, who, until now, have not paid taxes in the EU for profits that they generate in the EU.
I don't think the current US administration understand the EU.
There are some things where I have my doubts about the current actions of the European countries, like rearmament. Will that be dropped the minute a new US administration enters? What the EU does well, like really well, is trade and bureaucracy. It is, in my mind one of the few areas where the EU can absolutely run circles around the US, while managing to protect and isolate itself from the worst fallout. We've already seen this with the current EU tariffs, they are extremely precise and targets Republican votes at almost no cost to EU consumers. I think that will continue, rather than imposing broad tariffs, the EU will target things Trump care about specifically.
The DMA is already a tax on US tech companies specifically, given it is enforced exclusively against US tech.
Hence the retaliatory tariffs. The backdoor taxes through 'laws' (that are NEVER enforced against EU companies -- Spotify got a DMA carve-out).
This is exactly what I was thinking. Is not the US export far higher than import if they take into account the software and other IT services they sell? I would expect other countires to tarrif that.