President Barack Obama's healthcare law would not automatically collapse if the Supreme Court strikes down the unpopular requirement that most Americans carry medical insurance or face a penalty. The overhaul could still lurch ahead without that core requirement, experts say. But it would be more like a clunky collection of parts than a coherent whole. That would make an already complicated law a lot harder to carry out, risking repercussions for a U.S. health care system widely seen as wasteful, unaffordable and unable to deliver consistently high quality.