It would take something miraculous for the direction to reverse towards Europe. People have been complaining about European tech, economy, and freedoms (as in free speech) for decades now. Things have become worse on all of these fronts.

I think the AI act is a great example here. The EU came up with regulation for an emerging technology that basically killed the chance for Europe to compete. Lots of people disagreed with this criticism when the act was debated, but it turns out the critics were right. Europe will be buying AI services from elsewhere because Europe wasn't able to compete.

This entire way of thinking in Europe would need to reverse for there to be a chance that the brain drain changes course.

On the flip side, with the US cutting funding for scientific research, and increasing persecution of minorities within the US, I know a whole bunch of qualified scientists/researchers who are either moving to or actively hunting for a position in the EU