A manufacturing company is analyzing its demand forecasting process for a new product line. The company has historical sales data for similar products over the past three years, which shows a consistent seasonal pattern. The management decides to implement a time series forecasting model to predict future demand. If the average monthly sales for the last three years were 200 units in January, 300 units in February, and 400 units in March, and they expect a 10% increase in sales for the upcoming year, what would be the forecasted demand for March of the next year using a simple linear trend model?