In futurists' parlance a 'plausible' future scenario -- as opposed to a merely 'possible' or 'probable' one -- is a scenario that is not intuitive but can reasonably be anticipated from current conditions and trends. While it is not exactly an extrapolation of current trends and conditions, it is no more than a couple of surprises, or what futurists call 'wildcards', away from being so.
Plausible scenarios are more risky than probable ones in that they are less likely to occur, but they are potentially more valuable to have anticipated if they do come true. A plausible scenario is, using gambling terms, a long shot.