The decision of an organization to introduce product line engineering depends on a sound and careful analysis of risks and return on investment. The latter is computed by an economic model, which relies on high quality input and must reflect the envisioned migration strategy sufficiently. To facilitate risk analysis, this paper applies Monte-Carlo simulation to an existing product line economic model. Additionally, the model is extended by the support of product line generations that is, considering the degeneration of product line infrastructures and taking reinvestment into an existing product line into account. The practical application of the model is demonstrated by an industrial case study