Seems that travel patterns are not radically affected by testing requirements (whether in advance or on arrival). People who want to go somewhere -- whether on business or for leisure -- are unlikely to be deterred over a swab. Furthermore, travelers would be well-advised to obtain a negative result prior to travel in any event. While there are no certainties in life, if one is indeed positive, few really want to infect fellow travelers, those they may visit, and others. Even fewer want to risk what is potentially a life-threatening illness while far away from home and unable to return.