How can one generate future forecasts from probabilistic events?
If you have historical data on percentage of return for few weeks after the sales, I believe you can do it. It will be a multiple-output regression problem e.g. you will have to formulate the target values (i.e. output matrix) in a way so that %-return in first week will be in column one, %-return in second week will be in columns two and so on. After this, plug in all your input variables and run a multivariate multiple output regression algorithm. Such an algorithm on scikit-learn can be found (sklearn.multioutput.MultiOutputRegressor: here)