The transition may not be as jarring as some fear. In fact, it may not differ much from what younger workers have already come to expect. The average person will hold 10.8 jobs by age 42, according to the U.S. Labor Department. Younger people have grown accustomed to holding multiple jobs and are more comfortable with alternative work arrangements than their older colleagues. Technology might also speed the process. The use of e-mail, social networks and instant messaging enable the sort of remote collaboration that had previously been a stumbling block for shifting to a just-in-time workforce. But new problems may arise as the nature of the workforce shifts. Would the need for transient workers to hop from job to job mean they no longer have roots in a given area? Would frequent moves undermine the housing market? Would the lack of job stability take a toll on the mental health of workers? MacDonnell also sees numerous tax issues arising from the shift to a temporary workforce as companies adjust to new compensation models. -- Reported by Joe Mont in Boston.