Visa restrictions, export controls, national security reviews and travel scrutiny have added layers of uncertainty to decisions about where to live and work that were once framed largely as career choices.Li of RSIS described the trend as one of segmentation.Elite researchers, founders and executives may still have the networks and resources to move across borders - but the broader pipeline of students, mid-career engineers and early-stage entrepreneurs may become less fluid.That could have wider consequences beyond a simple talent redistribution from one country to another.“What stops moving is the tacit layer,” Li said.The deeper loss would be the movement of...