In scenario forecasting you accept as a given that the future is unknowable in detail. However, there is a structure to the future. The better way to look at the future of anything the supply of teachers or the pace of new technologies is to look for the structure in the uncertainty. The essential root of all four kinds of planning is the forecast. You cannot plan without a forecast of the conditions you expect to encounter.
Forecasts can be extrapolations of trends.
But trend is not fate. Trend-breaking events can be forecast, too, and accounted for in the planning period. The strategy is the work of the plan. Strategy is the integrative or connective tissue in the corporate plan that ties all the critical activities of the organization. Think what action of yours is likely to provoke rivals' greatest or least retaliation.