One of my websites has approx. 1000 backlinks. There are several PR7 and PR6 among them, many PR5, etc. It is 7 month old. It gets last month better ranking in Google (out of sandbox?) If I don't provide more content & links in next 6 months, would do you think how much would my traffic improve? How much more traffic (in percentages) you think I'll have after 6 months? 20%? 100%? 500? After 1 year? After 2 years?
impossible to determinate with good probabilities... as we don't know the values of the different parameters in the equation, we don't know all the paramaters of the equation, we don't even know the equation, just have a general idea of it (equation being ax + by +... gz = engine traffic to your site). so, impossible to tell