As a scientist in the US (on H1B visa), I really worry about other scientists postdocs/professors that were planning to come to the States and won't be able to (and will be out of the job, as very often your previous postdoc ends at the time when the new one is about to start). This capricious government is uprooting lives of people without any advance notice or concern. Essentially people are dealt with like cattle. Today you can go, next day you can't. (personally this is one of the reasons I'm moving back to the UK, where at least I don't have to deal with idiotic immigration laws).