To be realistic - no need to wait for 5 years and do all the math.
Another year and a half or maximum of two years should be enough to realize if one can be rich or not solely due to AVXL. Frankly, I am hoping it works out but am not banking on it - not yet, not till FDA /TGA/Other Regulatory body in Europe, blesses at least 2 of 3 CNS diseases ( Rett, AD and PDD/D).
If it works out I am sure your numbers will have to be revised to the upside.