This may be unpopular on an US-centric site like HN, but the US looks more and more like they want to isolate themselves from the rest of the world: very strict immigration policy, travelers molested by TSA on airports, ... These conferences where people around the world meet should start to be hosted somewhere else. Not in the USA anymore. Somewhere in a country that welcomes people instead of treating all of them l…
I would assume that for larger conferences the tendency won't be as strong, but it'll definitively be noticable.
I also see this when doing business; when interacting with companies where face to face interaction is needed there is a tendency to avoid business that requires travel to the US. Either they come here or we find partners outside the US. I know of several concrete business deals that have been made with non-US companies for precisely this reason.
It is tempting to think that this might end when the current administration ends, but it may not. The reason is that the last 6 months have demonstrated how volatile the policies can be in the US and how easily and quickly things can change for the worse. This affects long term planning. You don't want to make long term commitments when you have no faith in there being a moderating force to smooth out the more extreme forces acting on policy.