Why would they "normalize"? Do you think Microsoft, Amazon, Apple, Amazon, etc. are going to relocate to the EU or something? Are all the venture capitalists going to flock to Spain?
The mechanics driving compensation arent "normal." American pay is driven by the underlying mechanics. The USA didn't just randomly win at tech.
There are real factors that could reduce US compensation, but calling that "normalization" assumes the current gap exists for no reason. It exists because the US software industry is structurally different from most of Europe.
If demand for software developers decreases due to AI, salaries are likely to decrease as well. Take the academic world for comparison, where supply of very smart people vastly exceeds the demand.
> Why would they "normalize"?
Globalization? Look at manufacturing, it moved to a country where things are a lot more affordable. In a world where remote collaboration gets easier and easier and you're able to pay software engineers half the world away a lot less there's no way it wouldn't have an effect on the domestic market.